This circuit was found in a 73 magazine for radio amateurs of the 90s. The circuit uses two types of indicators, the diodes are for general use. The power supply is 5 V.
This circuit with LDR and neon lamp has its operating frequency given by the light. The circuit is from...
Originally designed for an incandescent lamp, this flasher or pulser can be adapted to operate with...
This circuit extends the scale of a milliammeter. We found it in a documentation from the 60's. The...