Test Circuit Request: Stop Current Before Wire End?

[giantkiller]

And you in all your pride would dare go against the magnetic almighty?

Foolish winder! May your pulses never saturate, may your winding never maturate, may your thinking never placate! Kicks are for geeks! Radiant rules!

--giantkiller. Hence the name. 3 days left. Do you know where your TPU is at? Git'r done!

[Spherenot]

Hi,
See my post #1152 in "user Turbo's replication of SM TPU",
http://www.overunity.com/index.php/topic,1761.msg21223.html#msg21223
on the CMOS version of the 555, the LMC555 or TLC555 (but not the MC1555), that run up to 3MHz in astable mode and the rise and fall time is 15nsec.  Also included in that post a link to an EDN design idea for a pulse generator with independently variable duty cycle and frequency adjustment possibility.

Thank you.  The link you posted there looks promising...

Help!  I built that circuit.

When I pull out the capacitor, (the lower one from diodes to ground,) I get a similar sized waveform reading on my scope as I would with a smaller, 22 pF cap.

I am thinking that the metal terminal rows under the plastic holes of my PROAM tester board have a kind of capacitance, limiting the smaller size pulses that I desire from my circuit. Am I right about this? 

[giantkiller]

Hi,
See my post #1152 in "user Turbo's replication of SM TPU",
http://www.overunity.com/index.php/topic,1761.msg21223.html#msg21223
on the CMOS version of the 555, the LMC555 or TLC555 (but not the MC1555), that run up to 3MHz in astable mode and the rise and fall time is 15nsec.  Also included in that post a link to an EDN design idea for a pulse generator with independently variable duty cycle and frequency adjustment possibility.

Thank you.  The link you posted there looks promising...

Help!  I built that circuit.

When I pull out the capacitor, (the lower one from diodes to ground,) I get a similar sized waveform reading on my scope as I would with a smaller, 22 pF cap.

I am thinking that the metal terminal rows under the plastic holes of my PROAM tester board have a kind of capacitance, limiting the smaller size pulses that I desire from my circuit. Am I right about this? 

Your proto can also gain oxidation on the contacts if the board has been sitting around unused for a spell or with parts left in it. I ran across this in the past myself with opamp circuits. You pull each part out & in but that is no guarantee.

I used to like to keep my circuits in prots as history and that doesn't work.

--giantkiller.

[gyulasun]

......
Help!  I built that circuit.

When I pull out the capacitor, (the lower one from diodes to ground,) I get a similar sized waveform reading on my scope as I would with a smaller, 22 pF cap.

I am thinking that the metal terminal rows under the plastic holes of my PROAM tester board have a kind of capacitance, limiting the smaller size pulses that I desire from my circuit. Am I right about this? 

Hi,

I second GK's opinion on boards/testers like you have, these boards inherently have distributed / structural capacitances.  The best would be to lift up the common endings of diodes D3 and D4  into the air and connect to them one leg of your small pF value capacitor and the other end of this cap will go to negative gnd, right?
By the way, you need really high frequencies like you would get by using 22pF? Maybe the R3 frequency control could also be lowered to 4.7-10 KOhm to boost frequency?

rgds
Gyula