FLASH SIGNAL ALARM

Schematic:

Notes:

This circuit is useful if you need a low-energy flashing alarm. The 200 to 400-dc supply should have enough internal resistance to charge the 0.5 uF capacitor between flashes, about 2 or 3 time constants, which means about 500k to 1M for a 1-s rate. Use lower values for higher rates.

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