Smallest Oscillator

401

07:05:56

4 components and oscillates in the FM range. It even acts as an FM transmitter if you replace the current source with a voltage source and resistor and vary the voltage of the power supply.

published 7 years ago

hurz

7 years ago

Not new and the replaced current source doesn't make it more realistic. http://everycircuit.com/circuit/4536554491215872

eekee

7 years ago

Only gets 13% slower if you increase the capacitance by 10 times! I don't think the visible capacitor is the primary capacitance in this circuit.

eekee

7 years ago

Hahaha! Increase the detached source to 200MHz and cut out the capacitor. It still oscillates! :) The oscillations are small though, and adding noise or increasing gain doesn't really help. I think the external cap just tips some balance between the parasitic capacitances.

eekee

7 years ago

C->500pF, L->30uH, source to 20MHz, timebase->150ns/s: still oscillates, but oscillations are very small, again. L->100uH, src->10MHz, t->300ns/s: ditto. Going to try a bit more, particularly watching the impedance of L at resonance. -- What is with all the people using parasitic capacitance to pretend they've made a smaller oscillator than I have? I EM FRUSTRATE! :D I'm half-joking, it is a little annoying but also stimulating.

hurz

7 years ago

@eekee, i think the parasitics 3 times 5pF can be seen like this http://everycircuit.com/circuit/4536554491215872

kiani

7 years ago

@eekee Cause you opened an interesting subject, in a nice way.

kiani

7 years ago

@Hurz now i undestand what EC is for. For indepth understanding,, it is an aid to understand,, and try new, or old ideas,, don't need to build large cct. To check out ideas. However still wish for sub cct. And library,. And a user guide written by someone like yourself,,.

hurz

7 years ago

Right, this is what i think everycircuit is for.

eekee

7 years ago

I think you guys are right. I'm sometimes driven to show off, but it's not really so good. Having said that, I have learned things from whole audio amplifier simulations, both mine and others.

eekee

7 years ago

This oscillator doesn't work at low frequencies, but testing it has given me an idea. :) Not working version: http://everycircuit.com/circuit/5533662656593920

eekee

7 years ago

My idea was to move the capacitor to the base, but then I realised that made it almost the same as my previously published pair. It's evidently possible to omit the base resistor and get a reasonable output.

jason9

7 years ago

My very small FM transmitter circuit is basically this circuit but without relying on parasitic capacitance. Because of that, you can scale it to lower frequencies with little to no problems if done right.

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