SSG modes COP

[MarkE]

Where's your coil?

[TinselKoala]

Very nicely done!

I don't know what the LED will do in place of the diode, though; I got better performance (according to my definition of "better" i.e. lower voltage operation) when I changed from the 1n4148 / 1n914 type switching diode to the 1n5817 Schottky.

Also, try the LED across the coil in both orientations. In either orientation, if there is too much voltage on the input this LED will light up, but when the device is working "properly" (again, by my definition) this LED will only show tiny flashes.

My coil measures about 11 mH and 36 ohms DC resistance. Around 900 turns of #33 on a small bobbin, air core of course.

[PhiChaser]

The coil I have tried is quite a bit larger I think; 30mm diameter,25mm tall, 62.5mH and 51.6ohms resistance (500+turns of 32? no idea... came out of a shake flashlight). I will post a shot when I get it working properly. Without any battery I can put a neo in the coil and get the main LED to flash when I pull it out of the coil, if done quickly the second LED will eventually start a low flicker.
Some things that I have found interesting; I can get the (main LED) flash if connecting the coil to both ends of the positive rail. I can also get the flash when connecting the coil from the neg input to the pos output (but not the other way around).
I might end up putting that diode back in... I don't have any Schottky diodes.

Phi Chaser

EDIT: For lack of pnp transistors I built another using three parallel caps (2220uf total) and a spot where I can test 'stuff'. I did find a germanium pnp transistor and it let one of the LEDs stay lit for a little while... Uploaded a pic of my second build.
Should this pendulum circuit be a new thread d'ya think?

[TinselKoala]

The shake flashlight coil is kind of large in inner diameter isn't it? And I found that my build works best with a coil that is nearer 10 or 11 mH and 30-40 ohms. I made a bigger one, around 75 ohms, and it works to pulse OK once the pendulum is swinging, but can barely trigger, so it is very difficult to self start. The one in the videos is closer, and I made a third one that is even closer to 10 mH and 30 ohms and it seems to work the best.
I think that for the pendulum you may want to wind a coil of smaller inside diameter, to focus the field more tightly over the end. The original Nuts&Volts article specified a bobbin, and I actually found the spec sheet for the exact bobbin. I made my own of almost the same size out of a section of phenolic tube 1/4 inch ID and some end plates cut from thin plastic or phenolic sheet.

Bobbin spec drawing below: (inch dimensions, sorry)

[PhiChaser]

Yep, the inside of my coil is about 1/2" (inches, mms, whatever works!), I took a closer look and it is probably closer to 1000 turns. The neo fits neatly inside the coil so I figured it would probably work okay for the pendulum...
Thanks for the dimensions on the coil you are using, I will see about winding something that has a smaller inside diameter (closer to the specs) and see if that works better.
Hopefully I can figure out some sort of stand to hang the weight and mount the coil on so I can actually 'watch' it working...
I need to order some parts or go find another 'something' to take apart for pieces'; seems like all I have are npn transistors and I'm running low on caps...
PC