Since the frequency of oscillation is governed by R2, R3, and C2 and assuming you are using +/-10% tolerance resistors you may see a range of 27.5-33.6kHz and that's not even accounting for the cap, C2. If you're actually using 20% resistors your range can vary as low as 25.25kHz. So 21kHz is still a little low but not outside the realm of reason. A quick experiment would be to swap resistors in your breadboard ans see what variance you get there but I doubt this is your problem.
Another thing that's important to check is your feedback node: collector of Q2. If the base is never being brought above ~0.7V then your oscillator won't shut off when it should and you'll end up with move than the desired 170V at the output. I'm not sure how far it can run away but it would certainly lead to components being fried because your FET drain would see higher and higher voltages before the diode turns on, potentially damaging the FET. Try disconnecting the diode on your breadboard and applying a 12V DC to the output node (where you expect 170V) and see what voltage you measure at the base of Q2. Do this with the oscillator unpowered (no 12V where it usually goes, just where it usually doesn't). You should see about (0.7/170)*12 = 49.4mV. If its much higher than that you are likely getting too great of an output voltage and it's burning out you FET. Just a though. I haven't built this circuit yet but I've spent the last few evening learning about it in detail. If I've said anything grossly in err someone should correct me! :) Cheers, Steve On Nov 22, 6:07 pm, Imbanon <imba.a...@gmail.com> wrote: > If I had such money, I would buy a scope instead :D > > Anyways, I just tried the frequency measuring function on the scope. > On the breadboard I got 32kHz which is great. On the other hand, I've > got only around 21kHz on the PCB which is 100% copied from the PDF > instructions. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
