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Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)
- Thread starter bushtech
- Start date
I think only if you want to fiddle around with storing data.
As i see it I have 2 options for separate power:
1. Use some 18650's, got plenty and enough chargers
2. Use the second tap on the transformer via a bridge rectifier, was going to use use it to build a - rail but don't think that will ever happen. If I use the second tap will it affect the power supply's readings?
As i see it I have 2 options for separate power:
1. Use some 18650's, got plenty and enough chargers
2. Use the second tap on the transformer via a bridge rectifier, was going to use use it to build a - rail but don't think that will ever happen. If I use the second tap will it affect the power supply's readings?
I am trying to set the power supply's 0V. All pots turned right down, no dummy load attached. DMM set to 2V and connected to the 2 output leads. DMM reads a steady 0.6V and turning RV2 (the 5k pot) I see no change. Pin 4 of U3 reads -1.37V. Have checked the RV2 pot and it works, 0 to 5k both ways
Maybe your output transistors are leaky. The output of U2 should go from about +30mV to about -30mV and the output of the circuit with a load should be adjustable down to 0V.
Check the input pin 3 and the output pin 1 of U2 for 0V. The output of U2 will normally go negative when trying to reduce the leakage of the output transistors.
Check the input pin 3 and the output pin 1 of U2 for 0V. The output of U2 will normally go negative when trying to reduce the leakage of the output transistors.
Back relevant to running your metering on an isolated power supply.
If they left an open hole . . .and your mounting method has left the hole in the "donut" open, you can wind your own dedicated and ISOLATED single power winding with much lighter gauge wire . . .30-32 gauge . . . and accomplish your slave meter power needs from that same toroidal transformer.
I would probably be choosing Kynar wire wrap wire for my choice, due to its small size and tough insulation . . . as being compared to just enamelled magnet wire.
If they left an open hole . . .and your mounting method has left the hole in the "donut" open, you can wind your own dedicated and ISOLATED single power winding with much lighter gauge wire . . .30-32 gauge . . . and accomplish your slave meter power needs from that same toroidal transformer.
I would probably be choosing Kynar wire wrap wire for my choice, due to its small size and tough insulation . . . as being compared to just enamelled magnet wire.
Wow St Edd, what a brilliant solution! I love your lateral thinking. I am sure the guys who wound my toroidal must have oodles of wire and hopefully what I need. Roughly what length of wire do I need?
I will now approach Dr Google for assistance in how to design and build your own transformer
I will now approach Dr Google for assistance in how to design and build your own transformer
Herr Bushmeister . . .
You basically need to have the metering circuitry battery powered initially, so that you can figure the current required at that voltage level . Then you relate that to an equivalent resistor.
E.G. the metering unit circuitry is using 5VDC ??? and pulling 500 ma of current if LED technology, or infinitesimally less if LCD.
That equates to a 10 0hm load. You then close wind / cluster 10 turns of loose wire thru the donut hole and hold it close together and twist the leads a few times to keep it from going s..p..r..o..i..i..i..n..g.
Solder the resistor to the lead ends and power up to see exactly what AC voltage is being developed with those 10 turns across your simulated degree of loading..
Say that it produces 4 volts with that 10 turns then you can see the proportional extra turns needed to get ~8VAC, since you want to overshoot, so that a FWB and its storage / filter capacitor and a following 3 term regulator and additional filtering can finally regulate you down to a stable 5VDC.
You can use wire from that manufacturer if he has that small of a gauge around, 32 is right at a 500 ma current spec while 30 is about 800ma.
PLUS copper magnet wire prices are ab-so-root-ley GOLDen now - a - days.
( And this is just a 1/2 of a lb . . .babycakes ! )
https://www.alliedelec.com/belden-8055/70004249/
For your initial testing, you can use a length of pulled out Cat-5 cable strands or phone wiring . . . . or heck . . .just use that entirely.
I have a 500 foot reel plus copious amounts of 50 and 25 ft lengths.
73's de Edd
.....
You basically need to have the metering circuitry battery powered initially, so that you can figure the current required at that voltage level . Then you relate that to an equivalent resistor.
E.G. the metering unit circuitry is using 5VDC ??? and pulling 500 ma of current if LED technology, or infinitesimally less if LCD.
That equates to a 10 0hm load. You then close wind / cluster 10 turns of loose wire thru the donut hole and hold it close together and twist the leads a few times to keep it from going s..p..r..o..i..i..i..n..g.
Solder the resistor to the lead ends and power up to see exactly what AC voltage is being developed with those 10 turns across your simulated degree of loading..
Say that it produces 4 volts with that 10 turns then you can see the proportional extra turns needed to get ~8VAC, since you want to overshoot, so that a FWB and its storage / filter capacitor and a following 3 term regulator and additional filtering can finally regulate you down to a stable 5VDC.
You can use wire from that manufacturer if he has that small of a gauge around, 32 is right at a 500 ma current spec while 30 is about 800ma.
PLUS copper magnet wire prices are ab-so-root-ley GOLDen now - a - days.
( And this is just a 1/2 of a lb . . .babycakes ! )
https://www.alliedelec.com/belden-8055/70004249/
For your initial testing, you can use a length of pulled out Cat-5 cable strands or phone wiring . . . . or heck . . .just use that entirely.
I have a 500 foot reel plus copious amounts of 50 and 25 ft lengths.
73's de Edd
.....
Last edited:
Hi Audioguru
Busy fixing 2 disastrous shorts (Have ordered insulated probes a la o/scope.)
After repair ended up with 31V on pin 4 of U3. After replacing D5,D6,2 x D7,C2,C3 and R3 I have got -13.3V on pin 4 (U3 removed) That only leaves R2, as an 82Ω 5W I very much doubt it can fail, reads about 80Ω.
Please I need your expert crystal ball again so that I can get to the elusive -1.3V on pin 4 of U3
Busy fixing 2 disastrous shorts (Have ordered insulated probes a la o/scope.)
After repair ended up with 31V on pin 4 of U3. After replacing D5,D6,2 x D7,C2,C3 and R3 I have got -13.3V on pin 4 (U3 removed) That only leaves R2, as an 82Ω 5W I very much doubt it can fail, reads about 80Ω.
Please I need your expert crystal ball again so that I can get to the elusive -1.3V on pin 4 of U3
Thir (lisp) bushtech . . . .
Also got a big roll of the stuff. If you use the cable as is, do you solder all the cables together at the ends, or how is it dood?
I just get as much length of cable as I am needing and then strip the WHOLE THANG of its outer covering and then separate the individual wires and take out the one that I need for that lengths entirety and roll up the separate wires into storage coils for future use of those lengths . . .or less.
With DC metering negative lead on the negative of your MAIN power supply filter and the positive lead to the shared R3-D7-U3 #4 junction . . . . . what is the level of NEGATIVE voltage being read on metering ?
( That counterpoise voltage reference presence is what lets you swing on down to 0 VDC, on
DC output voltage lower range. )
73's de Edd
Also got a big roll of the stuff. If you use the cable as is, do you solder all the cables together at the ends, or how is it dood?
I just get as much length of cable as I am needing and then strip the WHOLE THANG of its outer covering and then separate the individual wires and take out the one that I need for that lengths entirety and roll up the separate wires into storage coils for future use of those lengths . . .or less.
With DC metering negative lead on the negative of your MAIN power supply filter and the positive lead to the shared R3-D7-U3 #4 junction . . . . . what is the level of NEGATIVE voltage being read on metering ?
( That counterpoise voltage reference presence is what lets you swing on down to 0 VDC, on
DC output voltage lower range. )
73's de Edd
St Edd
With regard to the meters power supply, this is what I've done:
With bridge rectifier attached I get about 9V AC and 8V DC. Specs of meter say it can use a supply of 4.5 -24V DC. However when I connect the meter up it doesn't light up. Power it with a 9V battery and it lights up fine.
With regard to the meters power supply, this is what I've done:
With bridge rectifier attached I get about 9V AC and 8V DC. Specs of meter say it can use a supply of 4.5 -24V DC. However when I connect the meter up it doesn't light up. Power it with a 9V battery and it lights up fine.
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