Kapanadze Cousin - DALLY FREE ENERGY

[verpies]

Or does the "scope on 10x" statement apply to the horizontal sweep? , in which case you'd divide the numbers above by 10.  It's not clear to me just what you mean. Usually we use a 10x attenuating probe for voltage, so that's what I thought you meant. But if you  mean you've magnified the horizontal sweep by 10x, giving 50 ns per division, that brings your signal a lot closer to the "nano" range.

That's a good question.
If the horizontal sweep is really set to 500ns/Div then that is too much time.

[Hoppy]

I've been experimenting with the bipolar transistor drive circuit as per Dally's schematic. I don't have the specified KT926 yet, so have used an MJL21194. Its interesting that the specified 20R resistor is the optimum value which gives maximum drive current to the base of around 35mA. This is 10mA over the specified max for the 74HCT00N but at the very low duty cycle, this appears to be OK. With a transistor beta of 60, this would give a collector current of 2.1A. The waveform is not great but the added 1nF cap does clean-up the leading edge a little. The attached waveform (x1 probe) is the current waveform taken across the 20R with the 1nF connected.

Regards
Hoppy

[verpies]

I've been experimenting with the bipolar transistor drive circuit as per Dally's schematic. I don't have the specified KT926 yet, so have used an MJL21194. Its interesting that the specified 20R resistor is the optimum value which gives maximum drive current to the base of around 35mA. This is 10mA over the specified max for the 74HCT00N but at the very low duty cycle, this appears to be OK.

That might indicate that Dally's circuit is based in reality.

With a transistor beta of 60, this would give a collector current of 2.1A. The waveform is not great but the added 1nF cap does clean-up the leading edge a little. The attached waveform (x1 probe) is the current waveform taken across the 20R with the 1nF connected.

Was your scope set to 1μs/div ?
What is the pulse width out of pins 8 and 11 of the 74HCT00N when loaded only with 1kΩ resistor ?
In what range can you adjust the pulse width?

[Hoppy]

That might indicate that Dally's circuit is based in reality.
Was your scope set to 1μs/div ?
What is the pulse width out of pins 8 and 11 of the 74HCT00N when loaded only with 1kΩ resistor ?
In what range can you adjust the pulse width?

Yes, scope was set to 1uS/div.

Pulse width range from 460nS to 10uS. Same pulse width range when output loaded with 1K resistor.

Timing cap 1.5nF as specified.

Pulse width adjusted with 100R fixed resistor and 10K series pot as per your recommendation.

Regards
Hoppy

[verpies]

Yes, scope was set to 1uS/div.
Pulse width range from 460nS to 10uS. Same pulse width range when output loaded with 1K resistor.
Timing cap 1.5nF as specified.
Pulse width adjusted with 100R fixed resistor and 10K series pot as per your recommendation.

That pulse width range might be sufficient to elicit the DSR effect in some suitable diodes.
It is not surprising that you are getting 35mA out of 2 TTL outputs connected in parallel.

So how quickly can the 74HCT00N switch the MJL21194 transistor, from 0 to 2 Amps ?
In other words what rise/fall times are you getting with this setup ?