Hi
Just made up my JWPulser kit, but I can't get it to work.
I'll just go over the details. If anyone has a suggestion.
The 90v generates ok.
the led lights ok.
The collector measures just over 40v +- say half a volt but I can't get a reliable trigger on the jitter.
The emitter measures almost zero (~10mV) and I cant get a reliable trigger on the waveform. It should be spikes at an interval of 5 useconds.
The Base is interesting, see image, it peaks at 0.6v an decays down to 0.1v with an interval of around 6.5 useconds.
On the image, 0v is centred. This is exactly what I was expecting. I was expecting it should turn the transistor on and create the spike.
I think this is sort of avalanching but I am not sure.
With power off:
I measured 50 ohms on the output and 10k on the base and 1meg on the collector.
I have tried both 2N2369 and the behaviour is the same for both.
Also tried 2pF and 4pf, base of 3.3k and 33k.
I am measuring it with my cro lead, HP10017a which is nominally 10x, 1Meg and 8pF. I haven't got an adapter handy.
It picks up the base waveform ok.
Its almost like the emitter is O/C inside the BJT.
I measured the BJT I took out and it measures both Diode drops correctly.
Or maybe my cro has so much capacitance that the spike dissappears, it shows the base waveform though.
My ESD precautions were not perfect, but I was quite careful with the BJTs, put them on last and carefully. No wrist strap but not moving and keeping myself and tools grounded as best I can.
the other thought was that the legs were around the wrong way, but I have checked Free_Electrons images and the datasheets and measured it the connections seem correct.
Also in the photos you can see I haven't snipped of the Collector leg, I did on the first BJT but I wasn't going to do the second until it was all working.
Any ideas, anyone?