Sunday, July 29, 2018

Poor man's double sided circuit build of a 3 JFET amp.

The ground plane is very important and a good practice is to use a double sided board. Making one foil +Vcc and the other -Vcc. So what do you do if you have no double sided circuit board? Order some from a supply house or maybe just what you have available and make your own.
This old rough cut 2 X 4 is what I was looking for. It was used to chock some material shipped to a construction site. It would be land fill had it not found its way into my shed.
I chopped a short piece from the end of one to make it easy to handle. The sliced some thin pieces from it. I did not measure just something around 1/4".
I laid it on a magazine so I don't make a mess on my desk top.
I applied a coat of contact cement and get some aluminum foil for the laminate. What I'm using is not as thick as you might like but it was in the shop.
After the glue set for a couple of minutes I applied the foil.
I turned the page in the magazine to get a clean surface and laid the blocks facing up. Apply a coat of cement.
After a couple of minutes fold the foil over on the blocks and let it set a while so the glue can cure.
A sharp knife or razor blade can be used to cut the laminated blocks out.
 And we now have three double laminated bread boards. You could use flashing or a can just whatever is available. I like the coffee can bottoms. They are large enough and flat. Hair spray cans are good too.
As you can see it is a little ragged. You can sand or file the edge smooth but as long as it doesn't short out a little fuzz will not hurt.

This one is a little crinkled. You can use a putty knife or old playing card to work out the wrinkles I just was sloppy I guess? It will work wrinkles and all just not as pretty as it could be.
The large breadboard is poster board. It is the amp I posted 2 or 3 post ago. The little one is the double sided board version. I left the leads full length on the poster board version so i can reuse the components.

I used the copper foil glass workers use to solder stained glass with to make my solder points. I mounted all the transistors on little insulated islands and then added the grounded components. The +Vcc being on the bottom foil I just drilled holes sized to the wire and the used a 1/8" drill to drill through the foil on top. this allows the leads to pass through without shorting. The little amp is a good one. I would think you could use any JFET available to you. The biasing may vary a little but the worst case would call for adjusting the source resistor.

I used pasta maker manhatten pads to mount the transistors.

If you don't have the board for the pads you can make them using copper foil or old tin can strips laminated to craft paper. Just use what's on hand and some imagination.

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