Another AM Transmitter

270

04:42:47

A low power transmitter. It does not even draw 10 mA but transmission still is good enough for small distance. Audio in on the free 46k resistor. Antenna is the open switch.

published 6 years ago

jpoulin0901

6 years ago

I like it. Can you say anything about the coil? Ie number or turns, core material/shape? What about that power supply? Is that meant to be 4 AA's? What about running from a 9V? How about the transistor? Does it really run at 1.7 MHz IRL? What were you tuning into it with?

jason9

6 years ago

Hooking it up to an AC voltage source of 60kHz (so I could see the effects on the scope) it looks more like FM than AM. The actual amplitude is unchanged (at least at 60kHz “audio”), but the frequency does shift up and down significantly with the voltage of the input source. Also, the output is extremely dirty with tons of harmonics. That means that every station listening in at a multiple of the frequency will pick up some signal, although maybe not as strong. Putting a filter at the end to turn the output a pure sine wave should catch all those harmonics and clean the output nicely :D.

schmobi2001

6 years ago

This circuit surely is no perfect transmitter. I wanted to build a minimalist and as low power possible circuit. I use a readymade coil with a fixed inductance. My small AM radio receives the signal fine @ 1431 KHz. If I come close with my hand to the coil the frequency changes slightly. I want to solder this together to remove parasitic capacitances.

jason9

6 years ago

Ok. If it works then it works.

jason9

6 years ago

Here’s a simple AM transmitter I made: http://everycircuit.com/circuit/4799376734289920 it uses a 500kHz source, so you’ll have to come up with your own oscillator for whatever frequency you choose.

jason9

6 years ago

Another: http://everycircuit.com/circuit/5457880264474624

jason9

6 years ago

Another: http://everycircuit.com/circuit/4744804225515520 this one isn’t quite as simple

jason9

6 years ago

Transistorless: http://everycircuit.com/circuit/6529658261864448

jason9

6 years ago

Transistorless and with filter: http://everycircuit.com/circuit/4950302150361088

jason9

6 years ago

High-Quality: http://everycircuit.com/circuit/5723134622957568

jason9

6 years ago

Why do I have so many AM circuits? http://everycircuit.com/circuit/5516082347769856

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