Mysterious Resonant Circuit

[eldarion]

transistor:    2N4401,     (from Radio Shack, box of 15)
Base Capacitor:   0.01J    (not sure what that means)
Top capacitor for setting resonance:  47J
Capacitor in LC reactive branch, 220J

I guess there is a naming convention for these, I saw it somewhere once.

EM

Base capacitor: 0.01uF
Top capacitor: 47pF
LC reactive capacitor: 22pF
Tolerance: +/-5%

EMDevices, do you live near a AM, FM, TV, etc. transmitting tower?  Also, I think your scope was set to 20ns--implying a frequency of 12.5MHz--is this correct?

Interesting to note that the 2N4401 is only rated for 600mA of current...

Thanks!

Eldarion

[Yucca]

Nice work EMdevices, thanks for sharing your findings

I am trying to replicate, have wound the toroid and I have all components except my transistor is 2N3904 (NPN HFE~100).

I will try and finish it tomorrow and then post info.

If it doesn't work or even oscillate, probably won't knowing my luck, then I'll get hold of the same transistor you have.

Regards, Fraser.

[poynt99]

Base capacitor: 0.01uF
Top capacitor: 47pF
LC reactive capacitor: 22pF
Tolerance: +/-5%

EMDevices, do you live near a AM, FM, TV, etc. transmitting tower?  Also, I think your scope was set to 20ns--implying a frequency of 12.5MHz--is this correct?

Interesting to note that the 2N4401 is only rated for 600mA of current...

Thanks!

Eldarion

i would say it might be 220p, not 22p

[giantkiller]

An inductor and a capacitor and a pulsed DC signal or spark gap are the only components that ring the bell.

--giantkiller. Wait for the rebound or reflection.

[eldarion]

i would say it might be 220p, not 22p

3 numbers followed by a letter always means that the value is given in code.  In this case, the code is 22pF with no zeroes following it.