This crystal or galena radio uses a germanium diode. C1 is an old radio variable and L1 has 100 turns of 26 or 28 wire in a 1 inch PVC pipe. The antenna must be a long wire.
This version is one of many that can be found on our website. We found it in Radio Electronics from the...
This circuit for common analog telephones was found in March 1982 Radio Electronics magazine. It...
Figure bellow shows how the 4510, a divide-by-1U, up/down counter with three-state outputs is...