Type of wires

[ElectronicsR]

Hello,
how to find wires and its types with capacitance of wires used in rs232??

 

[(*steve*)]

RS-232 is very tolerant. You can use almost anything.

With longer runs (higher resistance and capacitance) you tend to just lower the speed.

 

[ElectronicsR]

how to find capacitance of it?

 

[davenn]

how to find capacitance of it?

what run length are you going to be doing and what baud rate do you want to use ?

ohhh and what cable do you want to use ? shielded or unshielded?
CAT-5 ?

 

[duke37]

Make a coil and measure its resonant frequency with a known capacitor and a grid dip meter.
Use the cable instead of the capacitor to calculate the capacitance. The cable length must be considerably shorter than the wavelength of the frequency in use.

 

[AnalogKid]

From two websites:

The specification recommends 24AWG twisted pair cable with a shunt capacitance of 16 pF per foot and 100 ohm characteristic impedance.

The standard also states that the maximum cable length is 50 feet, OR the cable length equal to a capacitance of 2500 pF. The latter rule is often forgotten. This means that using a cable with low capacitance allows you to span longer distances without going beyond the limitations of the standard. If for example UTP CAT-5 cable is used with a typical capacitance of 17 pF/ft, the maximum allowed cable length is 147 feet.

The cable length mentioned in the standard allows maximum communication speed to occur. If speed is reduced by a factor 2 or 4, the maximum length increases dramatically. Texas Instruments did some practical experiments years ago at different baud rates to test the maximum allowed cable lengths. Keep in mind, that the RS232 standard was originally developed for 20 kbps. By halving the maximum communication speed, the allowed cable length increases a factor ten.

ak

 

[ElectronicsR]

What is the use of shield wires???
and to study more on it?

 

[AnalogKid]

Shielding a wire helps prevent the signal being corrupted by radiated interference. For RS-232, usually the cables are not shielded. When they are, eash wire is not shielded separately like audio or video cables. Instead, it is a single shield around the group of individual wires.

https://en.wikipedia.org/wiki/Shielded_cable

ak

 

[ElectronicsR]

hello,
how to study or calculate how much capacitance is generated between wires?

 

[ElectronicsR]

i have done experiment for capacitor dielectric with mica and air
i dnt understand in air than capicitor was more than mica

 

[ElectronicsR]

Hello,
The specification recommends 24AWG twisted pair cable with a shunt capacitance of 16 pF per foot and 100 ohm characteristic impedance.

That mean for 10 feet 16*10=160pf??

 

[BobK]

Yep, that is what 16pF / foot means.

Bob

 

[ElectronicsR]

i have done experiment for capacitor dielectric with mica and air
i dnt understand in air than capacitor was more than mica

How to learn this experiment.

 

[ElectronicsR]

how to know more for this wires.

 

[(*steve*)]

understand question to ask how phrase sense make a order words sorry I'm can't.

 

[ElectronicsR]

i have seen coaxial wire for tv communication what is that silver paper on it body?

 

[(*steve*)]

shielding

 

[ElectronicsR]

why the use of it and there is cu wire with plastic and circular cross wires after that shield...

 

[duke37]

Look up 'coaxial cable' on Wikipedia, it gives a lot of information there and details of the various types of coax.
By circular cross wires, do you mean braiding?

 

[ElectronicsR]

at this website it is written
http://www.showmecables.com/product/times-microwave-lmr-100-coaxial-cable-1000-ft.aspx

• Any application (e.g. WLL, GPS, LMR, WLAN, WISP, WiMax, SCADA, Mobile Antennas) requiring an easily routed, low loss RF cable

are scada also used this ??

• Impedance: 50 Ohm

what impedance mean here per feet 50ohms??