uA Hartley transmitter circuit – Puddle Walker

See description: This type of oscillator has got to be one of the least power hungry on the planet. Lidmotor showed us his version, from a circuit found at Overunity.com. His circuit drew just 3 micro-amps. My replication here was derived from having wound a 300 turn coil on a straw for another project and then taking that coil and winding 150 turns in the opposite direction, to form the coil needed for this circuit. That compares to the spec requirement of 50 turns one way and 25 the other way. The extra windings seem to be the reason why no ferrite rod is needed for it to run 🙂 The transistor is a common or garden 2N3904 Resistor is 10K 250K variable pot 4.7uF 50V capacitor It has run with any and every battery thrown onto it so far, flat or charged and i’ve noticed that transmitting range or beat frequency doesn’t change at all. The transmission range is out to around 6ft, barely detectable, but would i’m sure improve with a better transmitting aerial. Looks like a winner for experimenting with. Here’s Lidmotor’s circuit, with diagram to replicate: www.youtube.com

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