SSG modes COP

[TinselKoala]

I got my BC556B PNPs from a seller called "thaishine" on Ebay, I've dealt with them several times and am quite happy. Free shipping to US addresses, four days from order to delivery in my mailbox. $3.49 for 50 transistors, delivered! They also respond to emails right away for confirmation, etc.
Search for
"ebay  thaishine bc556b"

If you are outside the USA or can wait longer, I see listings for 50 at under two dollars, with a dollar shipping, coming from mainland China or Hong Kong.

Yep, you are going to need a suspension for your pendulum to see the real operation of the circuit, or make a small rotor to try it as a rotary pulse motor. You could probably make a linear version too, with the right magnets and suspension.

[synchro1]

One strand for output from a bifilar power coil, looped back to source, should produce some valuable coasting time.

[conradelektro]

@TinselKoala: I watched your pendulum videos and wonder, why the pendulum stays exactly above the coil.

I know that the pendulum is suspended exactly above the coil. But the pendulum should try to avoid the coil, specially in push mode.

Or is the pendulum in attraction mode, which would always pull the swinging magnet over the centre of the coil core?

Great build!

I got the BC557B instead of the BC556B (which has a lower collector-base voltage -50V instead of -80V, and a lower collector-emitter voltage -45V instead of -65V, the rest of the spec is pretty much the same). Should it also work with the BC557B?

Greetings, Conrad

[TinselKoala]

@TinselKoala: I watched your pendulum videos and wonder, why the pendulum stays exactly above the coil.

I know that the pendulum is suspended exactly above the coil. But the pendulum should try to avoid the coil, specially in push mode.

Or is the pendulum in attraction mode, which would always pull the swinging magnet over the centre of the coil core?

Great build!

I got the BC557B instead of the BC556B (which has a lower collector-base voltage -50V instead of -80V, and a lower collector-emitter voltage -45V instead of -65V, the rest of the spec is pretty much the same). Should it also work with the BC557B?

Greetings, Conrad

The pendulum is suspended by a "V" suspension so it only swings in one plane. It's hard to see this in the video, I'm sorry I didn't emphasise it. The two points at the top are 10 cm apart and the vertical height from suspension to magnet is 20 cm. I adjust spacing by raising/lowering the coil, which is just sitting on a plastic 1/4-20 flathead screw with a plastic nut under the coil. Screw head is glued to the baseboard, coil is raised and lowered by the nut. 3 or 4 mm space between magnet and top of coil. The system operates in repulsion, when the drive pulse happens it pushes the magnet away. The suspension's geometry is such that any disturbance winds up being coupled into the plane of the swing, so it doesn't have to be perfectly accurate in position above the magnet to self-start. As usual, try all four combos of magnet and coil polarity to get best performance with triggering and pulsing.

I guess that the BC557 transistor should work fine as well. The original circuit specified 2n4401 and 2n4403.

Thanks for checking it out! It is really a fascinating little toy, I have it running constantly on the light from the desk lamp which is on anyway. I stop it and let it selfstart every now and then. If it doesn't get a trigger pulse from the passing magnet, it pulses automatically every few seconds, which is how it self-starts.

ETA: If there is too much voltage supplied, the coil will stay on. Also the LED (in my build) should make only tiny, short, barely visible flashes when it is running properly. Also, try the LED both ways, see what happens.

[conradelektro]

The pendulum is suspended by a "V" suspension so it only swings in one plane.

@TinselKoala: Thank you for clarifying the suspension of the pendulum.

I see, the capacitor C2 1000µF provides a pulse every now and then for the self start.

I just have to build one. As you say, very very neat.

The circuit reminds me of the two transistor circuit for a pulse motor (which does not need any separate trigger means, because the Back-EMF of the drive coil provides the trigger):

https://www.youtube.com/watch?v=OqQSJjRJ6EQ

Greetings, Conrad