Bedini SG

[Sawt2]

This will be the first circuit I've ever soldered together so I have beginner's questions. Some I asked in my last post in case anyone would like to answer them, but I have another one at the moment.

I'm using the photo of John's circuit as my guide (it's attached to my last post), and I can't tell how the transistors are attached to the heatsink. Can anyone clue me in on this?

Little cap screws

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Physical details of constructing the circuit

This will be the first circuit I've ever soldered together so I have beginner's questions. Some I asked in my last post in case anyone would like to answer them, but I have another one at the moment.

I'm using the photo of John's circuit as my guide (it's attached to my last post), and I can't tell how the transistors are attached to the heatsink. Can anyone clue me in on this?

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It's the image from page 62 of the beginner's handbook. I was unable to complete the upload (the window freezes on me after uploading it from my computer. I'm using the Brave browser, which may be the issue).

Having had more time to think about it, I probably answered my first question, which put in another way was whether the copper strip can touch the transisitors without causing damage. I suspect it can given that the transistors are insulated. If this is correct, I imagine I may even be able to glue the copper strip to the transistors. Please let me know if that's correct.

My other question of whether you have advice about the best way to assemble this circuit remains (e.g. attach the transistors to the heatsink first, then x, y, z).

I've watched most of the video of Peter assembling the kit, and noticed that he adds an additional resistor (10w 12 ohm) to the circuit. Should I do that too?

He also says since the instructions are now for constructing the SG in the attraction mode, a heatsink is no longer necessary. This is surely a minor detail, but should I put one in just in case or just make the whole backing piece for the circuit out of plastic (or thin plywood?)?

[Aaron]

post image

I have a couple questions about the circuit shown in the photo of John’s machine.

Is the copper strip with the resistors on it just hanging in the air in front of the transistors supported only by all the wires connected to it, or is it touching the transistors or even attached to them (glued perhaps)?

In terms of copying the circuit in the photo of John's SG, any suggestions/tips about the order/manner in which to attach the different components?

Can you post the exact image you're referring to?

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circuit component layout

I have a couple questions about the circuit shown in the photo of John’s machine.

Is the copper strip with the resistors on it just hanging in the air in front of the transistors supported only by all the wires connected to it, or is it touching the transistors or even attached to them (glued perhaps)?

In terms of copying the circuit in the photo of John's SG, any suggestions/tips about the order/manner in which to attach the different components?

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Thanks. Being able to clarify what is and isn't important in advance is definitely a pleasure.

Other than soldering issues, the thickness won't slow down the current moving through the copper right?

I appreciate the clue about solderability. I'll cut a test piece and try soldering to it. If it doesn't work well I'll sand/grind it down until it does.

[Sawt2]

I've been moving slower than planned, but I'm getting there.

The base is done, I'll finish gluing the magnets on today or tomorrow, the coil core is in and I'll soon be cutting the wires and making the coil.
Then, though I know it's easy, I haven't ever made a circuit so I'm a bit anxious about it.
Looking at the photo of John's machine, I'm thinking of cutting a flat plastic lid or similar to attach the copper strips to - that the majority of the non-transistor parts are soldered too. Copper strips are not available locally, though I could probably get them if it's important, but I'm thinking of cutting open a copper tube, flattening it out and super gluing or hot gluing it to the plastic backing. Will that work? If so, is it better that the copper strips be thick (the walls of the tube are an 1/8" or so thick), or should I try to thin them out (I'd probably use a grinder and/or sander)?

The thicker metal could make it a little challenging to solder, but other than that you should be fine. Also i don't think a foot of wire one way or the other will keep you from a successful build.

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Wire length

I have a 150' measuring tape. With some help, I'm planning on using it to measure the wire. Due to slack in the tape or wire, my wires may come out a few inches off. Is there any special harmonics or something about 130'? If my wires come out 129 1/2' or 131' will it make any difference?

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Circuit

I've been moving slower than planned, but I'm getting there.

The base is done, I'll finish gluing the magnets on today or tomorrow, the coil core is in and I'll soon be cutting the wires and making the coil.
Then, though I know it's easy, I haven't ever made a circuit so I'm a bit anxious about it.
Looking at the photo of John's machine, I'm thinking of cutting a flat plastic lid or similar to attach the copper strips to - that the majority of the non-transistor parts are soldered too. Copper strips are not available locally, though I could probably get them if it's important, but I'm thinking of cutting open a copper tube, flattening it out and super gluing or hot gluing it to the plastic backing. Will that work? If so, is it better that the copper strips be thick (the walls of the tube are an 1/8" or so thick), or should I try to thin them out (I'd probably use a grinder and/or sander)?

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Thanks. That makes more sense to use the rigid material as the support for the coil.

[Aaron]

removable cores

I definitely want to do that as I'd like to try different core materials. What I'm picturing though is probably not "right", as it could even damage the coil.

I'm imagining removing the core from inside the tightly wound coil to swap it out for another core. Since the coil is tightly wound though I think it will either keep it's shape, or contract a teeny bit when the core is removed. If I'm wrong about that, this idea may be valid, but if it is too tight of a fit, there'd be no room to easily shove another core in and doing so might mess up the coil. I could try to reduce the friction on the new core by spraying some silicone, or putting some vaseline or wax on it, but I doubt that's the idea.

The other thing I can imagine is making a thin sleeve (a sm. cylindrical plastic bottle that either fits as is, or needs to be slit and adjusted then taped shut) to slide my core into which would allow me to easily remove it later. But I don't think that's the idea either, so please clue me in.

If you wind your core on a bobbin/spool, etc. you already have a sleeve, it is the empty air core going down the middle. Take another sleeve that fits just snug inside that one and fill your core material in that. The second inner nested sleeve will be removable.

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I definitely want to do that as I'd like to try different core materials. What I'm picturing though is probably not "right", as it could even damage the coil.

I'm imagining removing the core from inside the tightly wound coil to swap it out for another core. Since the coil is tightly wound though I think it will either keep it's shape, or contract a teeny bit when the core is removed. If I'm wrong about that, this idea may be valid, but if it is too tight of a fit, there'd be no room to easily shove another core in and doing so might mess up the coil. I could try to reduce the friction on the new core by spraying some silicone, or putting some vaseline or wax on it, but I doubt that's the idea.

The other thing I can imagine is making a thin sleeve (a sm. cylindrical plastic bottle that either fits as is, or needs to be slit and adjusted then taped shut) to slide my core into which would allow me to easily remove it later. But I don't think that's the idea either, so please clue me in.

[Aaron]

removable core

I thought the copper had some special benefit that I was missing out on. Now I feel good about the steel bicycle spokes I bought today.

I also got a plastic plumbing pipe to serve as the core for my spool. It's a bit thick, so I'm thinking of using my tablesaw (in an unconventional way) to thin it down a bit so the spokes are as close as possible to the wire.

Can you believe it, no more questions for the moment! Thanks again for the help up to this point.

If you make the core removable by using the plastic pipe, you can experiment with different core materials and document the difference.

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I thought the copper had some special benefit that I was missing out on. Now I feel good about the steel bicycle spokes I bought today.

I also got a plastic plumbing pipe to serve as the core for my spool. It's a bit thick, so I'm thinking of using my tablesaw (in an unconventional way) to thin it down a bit so the spokes are as close as possible to the wire.

Can you believe it, no more questions for the moment! Thanks again for the help up to this point.

[Aaron]

copper

Thanks.

Based on your comments, I think the answer to my other question is to go with the 1/16" iron wire in the core instead of the 3/16" ball bearings. I'll spray the wire with a little enamel beforehand to add a dielectric layer and slow down rust (it's humid here).

What's the advantage of the R45 welding rod coating (the copper) over regular 1/16" iron wire?

The copper won't do anything for you - I think it is just for conductivity for welding. That was used for a long time because it is inexpensive, readily available and simple to work with.