Epée beeper box construction

[telkanuru]

Let me think. No, only one would work. I am pretty sure it's a PNP. See above attachment for assembly.

[cowpaste]

Let me think. No, only one would work. I am pretty sure it's a PNP. See above attachment for assembly.

Lol, I just did it with an NPN and it works. I use the high output to drive an NPN into saturation, which "closes" the transistor and allows current to flow freely from collector to emitter. I re-read some parts of the tutorial posted above. The output of the 555 chip is apparently capable of supplying AND sinking current, so I bet that PNP setup could work too. I perfer to stick with NPN though because I'm pretty familiar with its operation.

Apparently you were right about the 555 timing chip not being able to supply enough power to operate normally while causing the buzzer to buzz. Thanks for the tip.

[telkanuru]

My mistake. As I said, I still need that EE degree

[Pepster]

I'm not an electronics buff, but here is my thinking on the guard problem:

All the buzz boxes I've seen only use the A & B prongs to complete a circuit, the C prong (which grounds the guard through the body) could potentially be isolated from the body, giving the guard a different potential compared with ground. A buzz box incorporating the C prong would then be able to measure a resistance distinct from ground.

The problem isn't that you're unable to measure a voltage, it's a matter of reference.

It's a fallacy that a given point in a circuit has "A voltage." Think of voltage like height, You also need to know where you're starting from. If I'm standing on a five foot ladder, which is in a three foot hole, with is 100 ft above sea level, how high am I?
The true meaning of the answer lies in both WHAT i measured, and where I measured FROM. The same with a voltage, I can measure 1.327 volts on my opponents bell, but that relative to the ground in MY buzz-box. My opponent's box is completly isolated, and therefore the ground on his circuit and the ground on mine have no relation whatsoever.

If you want to see this in action, get a voltmeter and two 9V batteries. Connect the negative probe of your meter to one battery, and the positive to the other. You should get no reading whatsoever.

-Pepster
- Who is a student of the Zen of voltages.

[Epeecurean]

Ah, this has been rehashed before! (see thread Computer Boxes )

telkanuru, pepster, cowpaste: have any of you made any progress in creating a wireless epee system which grounds out bellguards and distinguishes between single/double touches?