Help with SG build..thanks

[powerdraw]

First..thanks for this learning experience. I am a beginner in all this; built my circuit by the book and am now trying to trouble shoot why my trigger doesnt seem to be getting the trasistors to switch. Before I tear it apart and redo everything I was hoping find out a couple of things to rule out something I am not seeing. I see the plans called for C8 ceramic magnets 2x1x.5. All I could find were C8s that are 1 7/8'x 7/8"x 3/8". Should this slightly smaller magnet be ok to be showing some level of working? I did find a source for C11 magnets with the right dimensions but the strength seemed a bit much at 10 lbs; could C11 be used? Or should I be ok with what I have? My coil seems fine tested off the circuit with no shorts and produces good magnetism. I did remove two trasistors form the circuit and rechecked for gain and they were good. Any ideas anyone has would be appreciated! And thanks to John Bedini for providing this learning experience.

[Tom C]

try switching your trigger wire polarity, switch which side of the circuit they are attached to.

Tom C

[powerdraw]

Thanks..but no different switching the trigger wire polarity...so the magnets I have should be ok? Im afraid I might have messed up a transistor but did remove two from circuit and they still measured the gain they had when I put them in. I did the transistor screening circuit and also did the 100 ohm resistors with the 1k pot to adjust. If the trasistors still have the gain they are supposed to, can the transistor still be bad in any way as far as switching? Thanks...I will probably rebuild the whole thing over if I cant find the problem!

[wild weasel]

can you post a picture of your setup? and of the board?

maybe whe can see the fault

regards
weasel

[powerdraw]

Thanks..heres pics of the circuit and wheel. Guess I tried to be too artsy making things circular so hard to work on. Here in wheel pic I had reversed wiring to change mode of running but thing acts same either way. Seems like coil is not getting energized to run wheel. I do see a small voltage oscillating across trigger coil when wheel spins but seems its not activating transistors or if they are switching, the coil isn't doing its thing. Hey..thanks..
Also, I wondered if the coil shaft thickness is critical? Book only specified inside diameter to be 3/4" but is thickmess issue? Also, the neon light leads were identical length so wondering if there is any polarity issue with the lights and how to tell?

[powerdraw]

sorry..just figuring out how to attach so attached messy..

[Tom C]

your magnets will be fine, you just need enough to switch the core. sometimes you need a real good spin to get it to fire the first time, its not a self starter. I cannot tell if everything is "right" the way you have things wired up. re wire it flat, start with one transistor and the trigger and work your way up. use the standard electrical troubleshooting steps.

Tom C

[Tom C]

do you have all the magnets north out? start of coil (the inside wires coming out of the spool) should be on the bottom of the machine away from the wheel, and attached to the individual transistors. end of coil (last wrap off of the spool) is primary battery positive. core needs to run the length of the spool all the way thru. if it is not you are not getting enough voltage into the trigger circuit.

Tom C

[powerdraw]

Thanks Tom

Yes..thanks..I wired it exactly as you describe according to schematic with wires out the top of coil to battery connection and bottom ones to transistors. Top trigger to the tramsisor base through the resistor and the bottom trigger to the negative input trace.The attached pictures show where I wired to change mode of running per page 74, point 2 where it describes reversing coil wiring. The change didn’t change anything so I am putting it back and rebuilding circuit in an inline fashion for easier working on one transistor at a time as advised. If my transistors still measure their original gain, should they be ok? Worried if I got any too hot to cause them not to function properly??. Thanks for the assurance on my magmets! I did fill the core of the coil Paul Babcock style with #7 bird shot and it seems like a good working core...hopefully I will be back with my working machine in the near future. Thanks again everyone..

[powerdraw]

ps...do lights have a polarity? leads are identical length so guessing not?

[Tom C]

you have the wrong core.... wish you would have said so earlier. it is not working at all. you need welding rod R60 steel birdshot wont work. build it EXACTLY like the book says. anytime you deviate from the instructions you will have problems.

Tom C

[Ed_Morbus]

You use double magnets ?

[powerdraw]

Here's a rebuild of my "Edsel"..can see how things are wired as book instructs. Seems like wheel wants to run but having trouble finding sweet spot with the trigger variable 1k resistor in series with 100ohm resistors going to transistor base. Think I'll replace with 470ohm fixed resistors skipping the potientmeter. Also has anyone made their cores out of #7 birdshot as Paul Babcock describes? Also worried may have to rewind my coil tighter as I got having to do by hand and it got messy. If anyone sees any obvious faults with my circuit attached, let me know. gonna change my name to "Edsel Builder" ha ha..

[powerdraw]

Thanks..already building new core ..book says R45 welding rod..I ordered already..you mention R60..are either ok then? Thanks..

[powerdraw]

never mind soory..see you were describing the birdshot R60..I have the right welding rod ordered and will make new core ..There are NO other deviations from build so hoping I will enjoy positive results..thanks again Tom...and thought I did mention the birdshot in an earlier post but no one said anything..glad you did when I mentioned again! I hear you!!