How to not hear Mylie Cyrus when I am playing guitar?

[KrisBlueNZ]

Wikipedia article on impedence says that impedence of capacitor is 1/jwC. I don't know what the j is. Wikipedia article on impedence says that impedence of an inductor is jwL.

Don't worry about j. The important part of the formulas are:

XC = 1 / w C
XL = w L

where w is 2 pi f (and f is frequency in hertz).
So those formulas can also be written

XC = 1 / (2 pi f C)
XL = 2 pi f L

where f is frequency in Hz, C is capacitance in farads, and L is inductance in henrys.

I'm assuming that w is the period in seconds of the sinusoidal AC wave.

No, it's the frequency, in radians per second. The frequency in radians per second is equal to 2 pi multiplied by the frequency in hertz. In your case it's easier to deal with frequencies expressed in hertz (cycles per second), instead of radians per second, so the second pair of formulas above is probably more useful to you.

So those phasor diagrams are designed to allow engineers (and physics students) to use algebra instead of have to solve differential equations, according to Wikipedia.

Yes. That's because the reactance of a capacitor (Xc) or an inductor (XL) at any particular frequency does not behave like a simple resistance. With a resistor, the current at any moment in time is proportional to the voltage at that moment in time. So if you apply an alternating voltage across a resistor, and measure the current flow in that resistor, you will see a waveform that's identical to the voltage waveform, and is exactly in phase with it. When you're dealing with a capacitance, or an inductance, the current waveform is not in phase with the voltage waveform; the component has reactance, not resistance. I won't go into any more detail at the moment.

I have no clue why guitar pickup manufactures specify the DC resistance of the pickup, but don't specify the inductance and impedence of the pickup. Maybee its more people like that RadioShack manager who don't have very high technical standards but are very good salesmen so they don't need to have high technical standards because they can fool people.

Perhaps because it's harder to define the impedance of the pickup. It's easy to measure or calculate the DC resistance, but other characteristics depend at least partly on the guitar strings, as well as the pickup. For example the inductance can be measured fairly accurately with no strings on the guitar, but when there's a vibrating string near the pickup, that previously measured inductance does not tell the full story. I'm at the limit of my knowledge here, so don't ask me for any more details, OK?

but why is the impedence of the volume pot 500k if its DC resistance is only 7k?

The DC resistance of the pickup is 7k. The volume pot's resistance is 500k. That's the end-to-end resistance. The resistance you see at the guitar's socket depends on the position of the pot. When the pot is at full volume, the wiper (which connects to the socket) is connected to the top end, which connects to the pickup. So you will measure 7k DC resistance. You can try this measurement if you want. The 500k resistance of the pot track will be in parallel with the 7k but will make little difference. When the pot is around position 7, where there is 250k of track resistance on each side of the wiper, the output resistance will be around 125k. Actually you can measure this with a multimeter on resistance range, connected to the guitar's output socket. You will find a position on the volume control where the resistance is at maximum. This will correspond roughly to the volume setting where the cable capacitance will have the greatest effect and will attenuate high frequencies the most.

So this makes me think that 300pF 10 foot long cable and 500k volume pot should already be a low pass filter that attenuates signals at a greater frequency than audio frequencies, and adding further capacitance would just give less of a treble response.

Right.

So I could wrap my cables in aluminum foil to block out the RF, since we have established that adding more capacitance to a circuit with high capacitance won't do anything other than kill high end response; but then that would just increase the capacitance and kill the high end response, since aluminum foil wrapped around an insulated conductor is I have built a capacitor.

That won't help. My suggestions for avoiding Miley would be:
1. Clean all exposed metal parts of all plugs, and the contact points of all sockets, with isopropyl alcohol and a cotton swab. Press hard. You can use steel wool or emery paper to remove any corrosion but this may cause the metal to corrode again, more quickly. If in doubt, replace the plug or socket.
2. Make sure that cables are tidily and cleanly terminated in all plugs. Make sure solder is bright, and individual strands of wire are not frayed or broken.
3. Make sure that the screening in the cable is tightly woven. If it isn't, buy another cable. Also, borrow a good quality cable from a friend and see if that makes any difference. Also, use the shortest possible cable.
4. You may be able to modify your amplifier to reject RF on its input. But I don't want to encourage you to poke around in there. Let me know if those other fixes don't work.

So then my "project" is a waste of time, and there's nothing I can do to remove radio interference if I don't want my treble response to be affected other than (in order of lowest cost):
(1) don't record at night if don't want to record WBBM.

Why does the problem only occur at night?

(2) instead of building a low pass filter to attenuate RF, build a noise gate that only allows the strong signals generated by the guitar strings vibrating in the magnetic field of the pickups to pass and attenuates weak noises such as RF noises.

That's always a good idea.
What are you plugging your guitar into when you get this interference? Is it a guitar amp? Or are you going direct into a mixer or sound card?

(3) install electric outlets into my basement and record in the basement (probably not a good idea for me to mess around with mains since I'm new to this).

Yeah, probably not LOL

(4) build a one transistor short range super regenerative FM guitar transmitter and receiver tuned to a frequency not used for broadcasting and add in the damn low pass filter to attenuate RF in the radio receiver.

You could try that.

(5) buy a noise gate.

Good idea.

(6) buy a wireless guitar system to eliminate the capacitance of the cable altogether and make sure that the wireless receiver has a low pass filter to attenuate RF and use a 6 inch guitar cable to connect the wireless receiver to the amp.

Good idea.

(7) buy a better amp that was designed to remove RF.

Good idea.

(8) buy out Star 105.5 and WBBM and turn off their transmitters whenever I want to record.

LOL
Also... if there's room in the body of the guitar, add active electronics to it.
Also, make sure the metal body of the pickup(s), the strings, and any other metal components on the guitar are grounded to the socket metal. Check with a multimeter.

Okay, I searched for that search term and I found that what your saying agrees with Wikipedia. The cutoff frequency does not literally stop all frequencies above or below it, it attenuates the frequencies at 3db per decade (I think decade means 1khz).

No, a decade is a ratio of 10 times. But a single pole filter attenuates at a rate of 3 dB per octave, not per decade. An octave is a frequency ratio of 2 times. So for every doubling in frequency, the signal is attenuated 3 dB more.

I was curious ... dipole antenna ... 3.4 MHZ ... FM stations ... green oxidized penny ... Led Zeppelin ... classic rock station ... it turns out you don't even need a guitar to make a radio ... I think I heard air traffic control too ... cleared to land on runway 9 left ...

Dieter, you're one of a kind. Thank goodness!

the inductance of guitar pickups ranges from 1 Henry for single coil pick ups to 4 Henry for high output humbucker pickups. More inductance increases the output of the pickup.

OK, interesting.

I like being right. I'm used to everything I post on here is complete nonsense.

So is everyone else!

Your right! A 1 farad pickup ensures that the LC resonant circuit is in the audio frequency range.

You mean a 1 henry pickup? And what is the actual resonant frequency?

Okay, I Googled Q and bandwidth and I found that Google says that Q is a unit less concept that is the ratio of (2*pi*f*L ) / R .

Yes, Q is unitless. It stands for "quality factor" and is an indication of the sharpness of the peak in the response of a tuned circuit. A higher Q corresponds to a sharper peak, with steeper sides, and a narrower bandwidth.

Oh...so at that position 7, the wiper is connecting the two resistances (the resistance of the pickup and the resistance of the pot) in parallel instead of in series, and in parallel will actually lower the resistance since its the reciprocal.

Almost right. You've got the general idea.

I'll tell you what the inductance of my pickups are when I find out.

OK. That will be interesting to know.
When you know the pickup inductance, you will be able to calculate the resonant frequency for various cable capacitances, such as 300 pF.
The formula is
f = 1 / (2 pi sqrt(L C))
where f is the resonant frequency in Hz
sqrt() means the square root of the bit in parentheses
L and C are in henrys and farads respectively.

 

[dietermoreno]

UG really didn't go into the physics that much and pretty much told me to give up and: buy a better amp that blocks RF, buy a better cable that isn't 300pF, clean off cable tips with rubbing alcohol, test different cables to see if its one cable that causes the demodulation, and if all else fails buy an EMI removing power supply unit to remove ground wave propogation on the ground of the wall outlet for MW stations and for the FM stations and other line of sight and skywave propogation buy a noise gate if all else fails.

So yeah, they pretty much told me to buy stuff to solve the problem.



So I turned to the Seymour Duncan site for answers.

The Seymour Duncan site gave a nice chart of the LC resonant peak, although it did not specify the default capacitance it was using, so its anyone's guess if Seymour Duncan is using a high end (low capacitance) or low end (10pf per foot) cable.

Here is the link to the chart: http://www.seymourduncan.com/comparetones

My pickups aren't on there of course since my pickups aren't Seymour Duncan, but I think I can make a good guess that my pickups are most similar to Seymour Duncan's low end medium output humbuckers. It turns out that the "low end" is actually good for electric blues compared to the "high end" is for metal. by "low end", I am referring to pickups in the chart that aren't named after a guitarist and are not famous pickups I have seen my guitarist friends go after.

The Alnico II Pro
says:

DC Resistance:
Neck: 7.6 k
Bridge: 7.85 k

Resonant Peak:
Neck: 7.1 KHz
Bridge: 6.7 KHz

EQ: 8 / 4 / 7 (Treb / Mid / Bass)

Magnet: Alnico II Bar

Cable: Four Con.

Output: Moderate

So it appears that Seymour Duncan actually takes the impedence of the volume pot into account for tone and specifies the volume settings where the different tones will be found.

It appears that at lower volume setting of 4 (higher impedence) it has a cut off frequency that is good for mids.

It appears that at near higest volume setting of 8 (lower impedence) it has a cut off freqeuncy that is good for treble.

It appears that at volume position 7 is the magic position that has the highest impedence and has a cut off frequency good for bass.


So the practical conclusion for actually playing guitar is that the volume knob should be turned to 7 for a rhythm part, the volume knob should be turned to 8 at least for guitar solos, and the tone pot might as well always be turned to minimum impedence so it doesn't make a cut off frequency lower than it should be for a guitar solo.

That's what I've been doing for the past couple of months anyway without even knowing what impedence is, I've always just had the tone pot at maximum treble (which now I recognize as minimum impedence).



Lol the famous Seymour Duncan blackouts that my "hardcore" guitarist friends have, those pickups have a resonant peak of 539 hz. So that's why they are used for "hardcore" "breakdowns" and not used for guitar solos.




I wonder if anyone thought of having taps on guitar pickups so you could select the inductance to tune to a resonant peak so you could have blackouts and vintage all in one pickup.



Well back to the radio interference part, just to give you an idea of the broad band interference on the FM dial from Star 105.5, at my house in my car radio I can hear the station at about half volume and distorted at 105.3 MHZ and 105.7 MHZ. Then when I drove my friends home who live in McHenry, when I got to their house on the west side of McHenry which is about 2 miles away from McHenry Community College (MCC) where the transmitter is, at 105.3MHZ and 105.7MHZ I heard the station at full volume just distorted (must be the AGC on my radio that makes the volume the same), at 106.4MHZ I heard the station at about one-tenth volume distorted, at 104.3MHZ I heard the station at about one tenth volume distorted, and at 97.3MHZ I heard the station at a quiet distorted volume about the same sound quality as my FM penny radio I described in a previous post. So 2 miles away from the transmitter essentially I hear the station on every frequency in the FM band that has static when I am at home. OMG why does Mylie and Madonna have to be on every frequency why can't I live in Pleasant Prairee, WI where the rock station 95.1 is probably on every frequency.

My college, College of Lake County (CLC), also has an FM station, but it is a low powered transmitter since it is not-for-profit and student run. So the radio station at CLC is always played on the loud speakers in the school cafeteria, but probably can't travel much farther than the campus ground.

I suppose Star 105.5 probably also started out as a student-run station and then it was bought out and transmitter power was increased to spam the FM spectrum near MCC with pop variety hits.

I suppose that at MCC you can probably have a crystal radio in your pocket and listen through crystal ear phones to the campus station at volume as loud as a transistor pocket radio.

I never picked up Star 105.5 in my recording when I lived in Wauconda just a few miles east of Island Lake. As soon as I moved to Island Lake it is picked up quietly in every recording.

Funny thing is that when I look on a map of the transmitter, I found that I misestimated the distance to the transmitter from my friend's house in McHenry, and I found that the transmitter is the same distance as from my house, which is 5 miles. So it appears that what is just as important to radio interference from one station is that there are no other stations nearby. Island Lake is closer to radio stations in Lake County in the Chicago suburbs, but McHenry in McHenry county has that as the only station in McHenry county.

 

[KrisBlueNZ]

The Seymour Duncan site gave a nice chart of the LC resonant peak, although it did not specify the default capacitance it was using, so its anyone's guess if Seymour Duncan is using a high end (low capacitance) or low end (10pf per foot) cable. Here is the link to the chart: http://www.seymourduncan.com/comparetones

I can't see any chart there...

DC Resistance:
Neck: 7.6 k
Bridge: 7.85 k

Resonant Peak:
Neck: 7.1 KHz
Bridge: 6.7 KHz

EQ: 8 / 4 / 7 (Treb / Mid / Bass)

Magnet: Alnico II Bar

Cable: Four Con.

Output: Moderate

So it appears that Seymour Duncan actually takes the impedence of the volume pot into account for tone and specifies the volume settings where the different tones will be found.
It appears that at lower volume setting of 4 (higher impedence) it has a cut off frequency that is good for mids.
It appears that at near higest volume setting of 8 (lower impedence) it has a cut off freqeuncy that is good for treble.
It appears that at volume position 7 is the magic position that has the highest impedence and has a cut off frequency good for bass.

I think the line "EQ: 8 / 4 / 7 (Treb / Mid / Bass) means that you're supposed to set your equalisation controls (on the guitar or on the amp) to those positions. Treble control set to 8; Mid control set to 4; Bass control set to 7. I don't think those numbers relate to positions on the volume control. If they did, it would say so.

 

[dietermoreno]

I tried every outlet in the upstairs music room, the news is heard no matter what outlet is plugged into, and I found that the news is only heard when my guitar volume is up and I mute the strings.

When I have the volume on my guitar at minimum so that all if is doing is providing a source of ground so that mains hum is not heard, I've found that its actually the FM radio stations that are every where. When I face due west I hear the dreaded star 105.5 in my emulated headphones and when I face slightly east of north I hear the more desired 95.1 THE ROCK STATION. So the guitar has nothing to do with FM reception and the guitar is only involved in MW reception.

So its not an outlet grounding problem, just the air in the Chicago area is that saturated with MW and FM stations.

So could I try building a noise gate to attenuate the weak rectified radio signals?

I didn't try using another instrument cable yet. I only have one uncoiled 10 foot instrument cable. I've found that my 20 foot instrument cable makes a real good FM antenna and my coiled instrument cable makes a real good MW antenna. So yeah, I can't try another instrument cable because all of my other cables are even worse.

Even the worst yet is using a tip ring shield cable instead of a guitar cable, removing the guitar, shorting tip to shield with aluminum foil, and making a loop antenna to receive both the vertical and horizontal polarized components of the wave by wrapping the cable around 2 coat holders and the door knob on the door to the balcony which the balcony is facing due west of the transmitter.

Even worse is taking the above set up, adding in a 6 inch instrument cable to connect from nickle to amp, connecting a short wire from shield to shield to provide ground, connecting the TRS cable to the green spot on a nickle (all of my pennies that are semi conductors are dark but not green yet), and connecting the 6 inch instrument cable to the clean part of the nickle. Now I hear Star 105.5's shitty adult pop rock half as loud as the side band at 105.3 MHZ on the car radio when I'm in my driveway. So now I have built a crystal radio.

I could make the bad music even louder if I used an insulated antenna wire (insulated so it doesn't ground itself) instead of the TRS cable so that the 300 pF capacitance of the cable doesn't block out RF, but I think I'll stop now.

 

[KrisBlueNZ]

Yes, you could build or buy a noise gate.
I'd also suggest that you resolder all the soldered connections inside the guitar, and clean any switches (as well as the plugs and sockets). Only do the resoldering if you're confident you won't make a mess of the wires. It's easy to melt the insulation by overheating the wire. You need to remove all the old solder and add new solder, and make sure you don't leave the iron on the solder very long. If you do, the solder will go grey and crystallised; remove it and put new solder on the connections.

 

[dietermoreno]

Yes, you could build or buy a noise gate.
I'd also suggest that you resolder all the soldered connections inside the guitar, and clean any switches (as well as the plugs and sockets). Only do the resoldering if you're confident you won't make a mess of the wires. It's easy to melt the insulation by overheating the wire. You need to remove all the old solder and add new solder, and make sure you don't leave the iron on the solder very long. If you do, the solder will go grey and crystallised; remove it and put new solder on the connections.

Okay I'll try resoldering all the connections.

If the output jack solder connection came loose a week ago requiring me to resolder it before I could even play guitar at all, the other solder connections may also be about to come loose, and loose old corroding solder connection could be acting as a diode detector that can slope detect the FM signal.

I don't think the guitar has anything to do with it because the FM signal is still heard in my emulated headphone jack of my amp if I short the guitar cable tip to shield with aluminum foil.

but I guess resoldering loose connections in the guitar is definitely a good thing to reduce losses even if it doesn't remove the FM detection.

For your information, the FM station is only heard when I'm not playing the guitar (and it requires that the amp is at full gain and full volume), so it doesn't bother me while playing guitar, but as soon as II stop playing the guitar and the amp is still cranked to 11 then some strange things start happening (start hearing pop music).

Also, the station seems to be heard more easily with headphones than on a speaker cab, due to the higher fidelity of my Seinheiser phones (same effect for recording and then listening to the recording with headphones).

For more information, I think the detection is occurring inside the amp, because I tried several different cables and the cables all produced the same results. Also, another reason I think the detection is ocurring inside the amp is because when I connected a corroded penny to the cable and connected to an FM dipole antenna mounted on a coat hanger it didn't make the station as loud (or as clear) as I would have hoped; in fact, it sounded "more distorted" but louder. So that leads me to suspect that the "more distorted" is coming from a second rectifying junction (penny) and since it is a better rectifying junction it makes it louder. Loud enough with penny attached and moving the antenna in different directions to quietly hear all the local rock stations (WLUP 97.9, WDRV 96.9, and WIIL 95.1) by turning the antenna for the "tuning", in addition to the occasional one sided air traffic control communication picked up if I face the antenna perpendicular to O'hare, compared to only the local pop station (Star 105.5) can be heard with no penny attached and no directional dipole antenna attached.

I've already told you that Star 105.5 is pretty much bleeding into every station on my car radio and Grundig radio very quietly when the tuned station has a moment of silence or if I tune to an unused frequency. Its 1600 watt transmitter is 5 miles due west of my house.

Just a curiosity, does this bleeding in phenomenon occur by slope detection of tuning to a different frequency from the transmitter center frequency and the slope detection extends modulating frequencies to infinity to cover the whole FM broadcast band?

 

[KrisBlueNZ]

Okay I'll try resoldering all the connections.

It couldn't hurt. If you've been working inside the guitar and have been moving things around, you may find that some of the strands of the wires will break between the end of the insulation and the component they're soldered to. It's probably worth fixing them too, by throwing away the crappy part (assuming there's enough length in the wire), re-stripping for a minimal length and resoldering the connection quickly, so as not to melt the insulation (or you can make a heatsink from a pair of pliers with a rubber band around the handles, or buy little aluminimum clip-on heatsink thingies), using new solder.

When you're soldering a thin wire to the terminal of a component such as a potentiometer, a switch, or a socket, follow this procedure.

How to solder wires inside an electric guitar:

1. Cut the end of the wire cleanly using side cutters. About 1.5 mm from the end of the wire, use a sharp wire stripper or a razor blade circling the wire with minimal pressure, to make a clean complete cut in the insulation, and slide the insulation off the wire. The clean cut will allow the insulation to slide off without stretching the remaining insulation. (Stretched insulation will melt quickly and shrink back from the source of heat when you apply it, leaving more exposed wire than you want.) Twist the strands together.
2. Tin the strands VERY quickly. Use a soldering iron rated for 25W or less, with a clean and slightly tinned tip. With the wire sitting horizonally, apply the tip under the wire, near the end. Apply the solder to the top of the wire. As soon as the solder melts and flows, remove the solder and the iron.
3. Clean and tin the terminal you want to connect the wire to. Remove any excess solder using a solder sucker. Make sure the component is mounted in its final position inside the guitar, and tightened so it cannot rotate.
4. Orient the guitar so the terminal is vertically higher than the component. This is so when you heat the terminal, the heat (which flows upwards) will flow away from the component.
5. Position the wire so it is held firmly in position, with the end gently touching the terminal you want to connect it to, near the top of the terminal. To keep the wire firmly in position, you can rest a heavy object on it, or use a "helping hands" device (don't clip the wire too near the end or the clip may dig into it and damage it when it heats up). Make sure the wire won't move as you solder it. You generally don't need to wrap the wire around the terminal (this wastes length and makes it hard to remove later), or even bend it so it hooks onto the terminal. You can bend it a bit if you want.
6. Apply the soldering iron tip to the side of the terminal (on a flat area if there is one), a short distance (1~2 mm) below the point where the wire is touching it, and preferably not directly below the wire (use a different side of the terminal if possible). Don't touch it to the wire itself. Apply solder to the point where the wire touches the terminal. When that part of the terminal gets hot enough, the solder will melt and form a complete and clean connection to the wire, with a nice shiny blob that's not unnecessarily large but encloses the wire and has a large contact area with the terminal. Remove the solder and then the iron.

Try to get each soldering operation over as quickly as possible. If there's not enough solder on the joint, you can quickly push a bit more solder in, but there's no need to overdo it; it will just look bad. Don't remove the iron and reapply it later. Don't keep solder that's already been melted and solidified; it goes grey and crusty. Remove it and start again.

Never move anything until the solder has completely hardened.

When disconnecting wires from terminals, avoid keeping the wire heated for a long time. If the wire is twisted around the terminal it may be best to cut it as close to the terminal as you can, rather than pulling on it to try to unwind it.

I don't think the guitar has anything to do with it because the FM signal is still heard in my emulated headphone jack of my amp if I short the guitar cable tip to shield with aluminum foil. But I guess resoldering loose connections in the guitar is definitely a good thing to reduce losses even if it doesn't remove the FM detection.

To be honest, I don't think it would make a detectable difference to the signal from the pickups. But it's still a good idea to do it.

Also, the station seems to be heard more easily with headphones than on a speaker cab, due to the higher fidelity of my Seinheiser phones (same effect for recording and then listening to the recording with headphones).

That'll be partly because there are no other noises in your ears when you're wearing headphones, so you can hear quiet sounds more clearly, and partly because the headphones will have a better high-frequency response than the speaker cabinet, especially if it doesn't have a tweeter.

You'll notice you hear only the high-frequency sounds, and the high-frequency harmonics of lower-frequency sounds, within the sound being broadcast, never any bass at all. You may find that turning down the treble on the amp (if it has tone controls) will reduce the interference, although it will also affect the sound of the guitar. If adjusting the tone controls on the amp makes no difference, the signal must be getting into the amp after the tone controls, but I think that's unlikely.

For more information, I think the detection is occurring inside the amp, because I tried several different cables and the cables all produced the same results.

That's quite possible.

Does your amp have a metal case?

Does it have a three-pin plug with continuity from the earth pin to any exposed metal on the amp, and to the outside of the input socket?

I've already told you that Star 105.5 is pretty much bleeding into every station on my car radio and Grundig radio very quietly when the tuned station has a moment of silence or if I tune to an unused frequency. Its 1600 watt transmitter is 5 miles due west of my house.

I see. That's a problem!

Just a curiosity, does this bleeding in phenomenon occur by slope detection of tuning to a different frequency from the transmitter center frequency and the slope detection extends modulating frequencies to infinity to cover the whole FM broadcast band?

With a signal that strong, any nonlinearity in the circuitry will cause some amount of detection of the signal. As you say, since it's an FM signal, it will be a form of slope detection that's occurring, but you don't need much of a slope to extract a very quiet demodulated signal from a very strong RF signal.

 

[poor mystic]

I wonder whether the mains earth is good.

 

[dietermoreno]

I wonder whether the mains earth is good.

Resoldered guitar jack and problem solved. So it was the loose solder connection that was creating the rectifying junction, NOT the amp (although the amp still has a rectifying junction, just it is much much quieter).

That's why there was not a noticeable difference of using a green oxidized penny connected to an antenna wire instead of a guitar, because the loose solder connection was the same effect of using a green oxidized penny connected to an antenna wire.

Actually, the much much quieter rectification heard is probably more loose solder connections, so I should resolder all connections in my guitar and then there will be no more radio heard on my amp.

 

[CDRIVE]

Until fairly recently, it was relatively rare to see nF used. 0.001uF was common, as was 1000pF. And that was about where people changed from uF (or earlier mfd) to pF. It is still very rare to see mF, possibly because there is some risk of confusion with nF or mfd.

I stumbled in here while looking for something else. Fortunately when I saw Detro's name I prepared myself with tight, multi-layers of duct tape securing my cranium from flying fragments.

Anyway, I know we're long past this part of the thread but am I the only one that remembers when we specified pF as uuF or even mmF? I do prefer pF though.

Chris

 

[KrisBlueNZ]

Yes, I remember seeing schematics with values marked in µµF. They were drawn before my time though. These days nearly everyone is comfortable using standard SI engineering prefixes, which are defined for every three orders of magnitude - femto, pico, nano, micro, milli, (units,) kilo, mega, giga, tera.

Regarding the change to using nF, I wouldn't describe it as relatively recent. But perhaps that's because when I was learning this stuff in my childhood (late 1970s, early 1980s), I mostly read British magazines; I think in America, the change took longer to get established.

 

[CDRIVE]

Regarding the change to using nF, I wouldn't describe it as relatively recent. But perhaps that's because when I was learning this stuff in my childhood (late 1970s, early 1980s), I mostly read British magazines; I think in America, the change took longer to get established.

Honestly, I never used nF until I started using Tina. That's because when I type .1uf it automatically converts it to 100nF. I prefer the former because it takes up less real estate and because of the old dogs - new tricks thing.

Chris

 

[(*steve*)]

I remember the nano prefix being described in an electronics magazine as they moved from using pF and uF to pF, nF and uF.

I suspect it was a "standards" issue as I'm pretty sure it pre-dated the use of software to do this sort of stuff.

 

[CDRIVE]

Oddly, for me that is, nano isn't new. I've been using and seeing it for time (nS) measurement as long as I can remember. Just not for caps.

Hey, there was a time when I wouldn't draw a transistor without enclosing it in a circle. It was a hold over from my vacuum tube years.

Now where the hell did I put that Tickler Coil?

Chris

 

[KrisBlueNZ]

I stopped drawing circles around transistors and other active components a LOOONG time ago. I think it was because I liked the look of the "equivalent schematic" drawings on IC data sheets. They also have the gently angled collector and emitter, which join part way along the base, instead of the 45 degree lines that join at the centre of the base. I adopted those conventions a long time ago because I liked how they looked. As I see it, there's nothing so special about an active component that means that it deserves to be enclosed in a circle.

Now, valves (tubes) are a bit different, because they're so large and such an important part of the design from a practical point of view. On the very occasional occasions when I draw a valve (tube), I do draw an obround outline around it.

On schematics I draw for my own use, I use an extension of the BS1852 standard for component values. That standard states that the multiplier (or unit) is used instead of the decimal point, so for example a 4700 ohm resistor is written as 4k7. But according to the BS1852 standard, a 470,000 ohm resistor, for example, is written as 470k; I write it as M47, which means 0.47 megohms. This means that ALL values (at least, all E12 values) occupy three characters - one multiplier/unit letter, and two digits. The letter may be before, between, or after the two digits.

The standard BS1852 numbering could be three characters (e.g. 5k6, 39k) or three characters (120k, 680R). By allowing the multiplier/unit letter to appear at the start of the value, I made all value markings three characters long. Another win for standardisation/consistency, and less busy schematics!

Ever since I got familiar with the SI engineering prefixes, which was some time in the 1980s I suppose, I have been using them universally for all component values.

Just in case anyone is interested

 

[CDRIVE]

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Now, valves (tubes) are a bit different, because they're so large and such an important part of the design from a practical point of view. On the very occasional occasions when I draw a valve (tube), I do draw an obround outline around it.

That's not why I enclose vaccum tube elements in a circle. I do it because that was standarized symbol. Besides,.. how are you going to maintain a vacuum without it!

Chris

 

[KrisBlueNZ]

That's not why I enclose vaccum tube elements in a circle. I do it because that was standarized symbol. Besides,.. how are you going to maintain a vacuum without it!

LOL Chris

Seriously though, that's a fair point.