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Dave Schmarder's Electronic Breadboard


Dave Schmarder's Electronic Breadboard

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Breadboard for testing projects.

Updated December 2007

Hello radio experimenters! This nifty project is for you. I'm sure that you already know what it is, but for the newcomers, this is a "breadboard" designed to test your projects before doing the final build. It is easy to change the connections (solderless) and there is room to do the wiring.

The base is made from 3/4 inch (18 mm) oak lumber. After putting a nice finish on the board, I laid out the board so that eight modules could be mounted at any one time. The modules are made from 1/8 (3 mm) thick Garolite® cut to 4x3 inches ( 10 x 7,5 cm). They can be removed from the board or moved to different positions on the board. There are T-Nuts mounted under the board, so that thumb screws can be used to attach the modules to the board. Here is what is on the board, so far:

New! A dual-wide board with the tuning and regeneration functions all on one board. There are two 620 pF variable capacitors, one for the main tuning and the other used as a throttle capacitor. The coil has a main tuning winding, a tickler coil and an antenna input coil. Due to the tight coupling of this coil, it is best used with a very short antenna. There is also a 50 pF variable capacitor for coupling the antenna directly to the top of the tank coil. Included on this board is a variable grid leak resistor and variable grid capacitor.

A dual gang 365 pf variable capacitor and a 100 pf variable capacitor.
A filament rheostat, a 5k pot and a 50k pot.
A 7 pin and a 9 pin tube miniature tube socket.
Two 4 pin tube or plug in coil sockets
One 5 pin tube or coil socket.
Two octal surface mounted socket for a tube, coil or a relay.
Bogen T-725
MW spider coil w/tickler winding + Shortwave tapped coil. (this has been updated by the dual wide board described above)
Extra terminals + 10 mh RFC.
More to follow.

For handy terminal connections, I am using some Eurostrips.

Your design will depend on your needs and what is in your junk box. I chose the most likely used parts for my breadboard. I also have several blank modules, ready to be made into new component boards.

I may build some transistor oriented modules too. A module with terminals only would also be nice.

At the rear of the breadboard there are two T-Nuts mounted with the holes about 6 inches apart (15 cm). These are for other modules, such as an AC mains power supply or a battery supply. Perhaps I will build a small audio amplifier that can be used with what I build. A LM-386 could be a good choice in this case.

If you make one of these, send me pictures and descriptions. I may steal your ideas. All are sure welcome to my ideas. My special thanks goes to Mike Peebles for giving me the kick in the butt to get this project underway. He is a great butt kicker and my best eBay auction kibitzer.

Happy Building! Dave, N2DS

Dave Schmarder's Breadboard Tuning Unit

Tuning Unit for this breadboard.


Dave Schmarder's Breadboard Tuning Unit

Tuning Unit for this breadboard, back view.


Dave Schmarder's Breadboard Tuning Unit Schematic

Front End Tuner Module


Dave Schmarder's Breadboard Tuning Unit, module close up view

Close-up view of the 7 and 9 pin tube socket module.


Dave Schmarder's Breadboard, back view.

Back view of my breadboard.


Dave Schmarder's Breadboard Tuning Unit in use

1 Tube EM84 Radio.


Dave Schmarder's Breadboard Tuning Unit in use, 1 tube regen radio

1 Tube regen radio built on the board.


Dave Schmarder's Breadboard Tuning Unit in use, 807 tube regen radio

807 Regen Radio