testing buffer without really long cable?

[carboncomp]

Wanted to play about with some buffer circuits and am wondering if there is a way to simulate a really long cable on the workbench?

[antonis]

A rough simulation is to place a cap from signal (cable tip) to ground at about 40pF/ft (120pF/m)...

[carboncomp]

Thank you antonis!

A 40pF capacitor take up a lot less room in the workbench then a 40 foot cable!

[PRR]

> A 40pF capacitor take up a lot less room in the workbench then a 40 foot cable!

Check your math!

40 feet is more like 1,200pFd or 1,600pFd.

I've always found that 30pFd/foot (100pFd/meter) is a useful estimate, though I do not dis-agree with Antonius' 40pFd/ft (120pFd/m) numbers.

When I was driving 300-foot cables I just used a 0.01uFd (10,000pFd) cap.

Note that "some" buffers, driving 0.01uFd, with a supersonic square-wave (I test hard), can pop the transistor. This is quite unlikely in any musical application, but I re-designed that one to be pop-proof.

[antonis]

When I was driving 300-foot cables