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Resistor substitution box circuit

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M0BSW:
Hi Everyone , I've lost the circuit for a Resistor sudstitution box, does anyone know of a good no frills circuit.
thanks in advance
Paul

FenderBender:
They are all pretty much the same. Get 10-position rotary switches. Then you get 10 resistors per switch. So you'd get 10 of each type (1M, 100k, 10k, 1k, 100, 10, 1, 0.1 etc.) And then you put one of each of these resistors between the 10 pins of the switch so that each time you move the switch, you add (or subtract) a resistor to the circuit.

Dave also did a video on his own and a assembled unit.

You can use standard rotary switches or thumbhweel switches. There are cheap thumbwheel switches on eBay (quality is unknown, though they will probably work fine). You can also get BCD switches (binary coded decimal) which might seem trickier to setup but they are actually just as simple as a 10 position switch.

Circuitous:
For a diagram and example, see:
http://kripton2035.free.fr/LabTools/lbt-resistordeca.html

Decade switches like the ones in the example are available on ebay.  If you're in the US, an easy place to order these from is Adafruit.com
Here's a link to the large size http://www.adafruit.com/products/1082
  $7.50 for a pack of 5.

george graves:
Here ya go..... http://www.digitalunderpants.com/?p=219

M0BSW:
 Hey thank you everyone kind enough to answer, I thought they were more complicated than that , really appreciate your help
Paul  :-+ :-+

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