Lords of the Ring

[Jdo300]

Hello Everyone,

I just finished some more testing with my self-triggering coil circuit. My goal tonight was to see if changing the coil in the circuit made any difference to the frequency that the MOSFET pulsed at. I tried three different coils (see pictures below) and there was no difference in the frequency! It was rock solid! The only noticeable difference was a slight rise or fall in the amplitude of the waveform.

Next, I tried changing the MOSFET that I was using. I started off with an IRF840 but also tried an IRF640 and an IRF510. All of them still had the same basic frequency.

1st harmonic ≈ 4.032 MHz
2nd Harmonic ≈ 8.33 MHz

This was using the 40 nF ceramic cap across the gate and source.

My final test was to change the capacitance on the gate to see if that varied the frequency. My results of that test are inconclusive at the moment since I used a 320 pF radio tuning cap in parallel with the ceramic cap. I believe that I was able vary the frequency by +-10 kHz but I want to use a larger tuning cap to see how dramatically I can do it (if it is possible).

NOTE: Coil inductance measurments taken with a JT-33 LCR meter.

God Bless,
Jason O

[Jdo300]

@ all  The coast to coast thing was more like my version of "go sign it on the mountain", I just didn't think that held context here.

Btw I am still a bit lost as to the progress, I understand the self oscilator, but I haven't seen a report/explaination of the connection to the coils and how everything it working together for a net yield.

I too am fond of games, however I don't have to eq to play in this one. Heck I am just happy to have figured out how to get an automotive coil to fire up on my desk, I was killing 555 chips with 12v. Let me tell you everything on the desk freaks out my meters all max out in volts(connected to wires or not) and it only uses .015amps @ 120v. No wonder tesla loved coils, they are interesting. wifi drops out, wirless keyboard freaksout computer reboots. Its fun.

Good luck at the team, have fun stormin the castle tonight.

Once the oscillator is created and can self-oscillate, then all you need to do is loop some of the output from the collector to the input of the MOSFET to pulse the coils. Hence, no 555 timers necessary! But one needs to understand how to properly tune the thing to make it useful. The good news is that this circuit appears to be a very stable oscillator and it locks into its frequency no matter what coil is placed on it.

One step at a time...

God Bless,
Jason O

[innovation_station]

congrats to all!!

it seams i will be reading some more

the fun continues

[Rosphere]

My results of that test are inconclusive at the moment since I used a 320 pF radio tuning cap in parallel with the ceramic cap.

Jason,

Why not just swap-out the one cap for another one, like you did with the coils?

I am still squirming with my paradigm-shift to use other than one 9V battery to do your MOSFET circuit test and future tests.  As I wrote GK, after seeing what a coil can do to a frequency I can not help but wonder if our coils are coaxing some extra power from the wall outlets.  He insists that it is valid shortcut for now.  I suspect that it may lead to dead ends.

I want to use my 12V camper battery but folks say, "danger, Will Robinson, danger!  Too much current."

I found an, "INPUT:AC120V 60Hz 8.5W, OUTPUT:DC12V 400mA," black-box converter that I measure at 18.4 volts.  The AC portion of the output on my scope looks like white noise around 20 mV thick. (I hope you understand in spite of my ME spin on an EE description.)  Would you use this to do your test?

Rosphere--Questing...

[weri812]

to all 

got a scope coming  and a square wave gen coming to day

are we trying to keep the power supply to 1-3 9 volt batterys
to keep this  small for now?

wer