Bedini Schoolgirl

[Jetijs]

I can't see the output diode from the collector.

[Jan H]

if it wants to start by itself something is wrong, it should not do that as far as i know.
maybe isolate your coil and see if there is any conductivity between the two diffrent strands, there should be none.
Are you sure the field created is right? i also did measurements with a compass, and it's real easy to make a north/south mistake. it should repel the magnets when power is applied.

[hydrymoron]

Re. Diode query

Output diode? Duh, I thought the simplified model only needed the diode on the base as in the diagram in this thread? I'll put that in and give it another try.

[Jetijs]

use the circuit shown here:
Bedini_Monopole3 : Bedini_Monopole3

[hydrymoron]

Re. Diode query

I've been following the instructions up until now for the simplified circuit with only the primary battery connected., and using this diagram and the JB one. Are you saying that this is not a working circuit as it stands, and that I need to add the charging side? I tried connecting the second diode to the first battery, but I see that that's wrong.

[Aaron]

schematic is good

That schematic is fine as it is...that would be the bare basic SG and is the starting point.

The diode leaving the collector is just to send the collapsed spikes to a recovery battery or cap, etc...

You don't need that for it to run...the schematic you posted is perfect.

In your pic, what is that blue thing ahead of the resistor going to base?

Also, you probably have it right, but make sure you don't have the Base pin and Emitter pin on the transistor backwards.

[hydrymoron]

The blue thing is a variable resistance, which at the moment I've got set to zero with the fixed resistor at ten ohms. If I bridge that resistor with the meter on 1 ohm test, with the positive probe to the right, the coil begins to oscillate and with a compass behind the coil, the rear of the coil starts to show south. If I do this without the core in, I only need to give it a quick touch and then it continues oscillating and when I jack up the resistance, the whine rises in pitch.

I've double checked the transistor connections for the 2n3055, and all the pin arrangements show it as I've got it connected. I took the transistor off and tested it, and it seems OK.
Just a thought. Does the battery need to be in prime condition? Mine is off an old scooter, and I suspect its a little past its prime, to say the least.
One other question if I may. What should the air gap be, and how critical is it? I've tried everything from practically touching to an inch away or more.

[hydrymoron]

Re. Diode query

Here's another pic from above, in case it helps.

[Aaron]

sg problems

It helps to have a battery in a good condition but I have run a roller skate motor on 9v alkaline battery and that worked and it wasn't fully charged. That was probably the smallest power I put to these.

Is it possible the variable resistor is problematic? Can you put connect a wire on both its leads to by pass it and see if that works?

1/2 cm is a workable air gap...are those neo magnets you're using? If so, they will be too strong if too close to the core..can still work through.

[Aaron]

core info?

What are you using for a coil spool? Almost looks like a green skate wheel. Probably not with that many turns...for a core, it should be pretty close to the inner turns of the coil...if there is too much material gap between core outside and inner turns, there might not be enough induced current at the coil.

[ren]

Aarons right, try moving your coil closer to the rotor, and make sure theres not too much gap between core and windings. Also, if your a visual person like me you'll find this diagram easy to follow. The 2n3055 to3 transistor is mounted upside down inside the heatsink with the prong (base and emitter) sticking out.

[Tecstatic]

Improving COP

Moved post to "electric motor secrets".

[hydrymoron]

Re. Diode query

The coil spool is a plastic spool, originally for solder, with an inner diameter of about 2 cm. I've tried various things in the core, first a cluster of thinner steel bolts, then a piece of cast iron and now the fattest bolt I could find, which is quite a bit thinner than the spool core but has a quite wide head and nut.
The 2n3055 is connected with the base on the left and the emitter on the right with the transistor on its back and legs in the air (!) with the pins above the centre line.
I've tested (and tried bridging) the variable resistor.
I've tried about every gap position I can think of.
Later I'll try it in the car, just to eliminate battery possibilities.

[hydrymoron]

Re. Diode query

I got it to run!

I tried it out on a 12v car battery. No dice. The I tried bridging the 10 ohm resistor with the meter on th 1ohm setting and with the positive probe nearest the coil, and off she went like a bird!. This also work if I do the same thing with the input diode and even bridging with the same probes from the base to the disconnected output diode soldered to the collector (although not so well). there's obviously some cock-up in the wiring here, but I can't see it.

[Aaron]

good to hear!

Glad to hear you got it running!

You can probably run it on a much smaller battery if the
you fill the core with as much iron as you can. If the bolt
itself is smaller than the core, there is too much space
between the bolt and the wires. Even if the head is bigger,
you really need that iron right up next to the windings.
Maybe you can jam in some smaller bolts around the larger
bolt if there is room?