This is part 3 of the Thermin build.
The earlier parts are here:
Part 1
Part 2:
This is the build so far.
Resistors, caps, IC headers, trimmers are in.
There are two types of Diodes:
1n4004 x 4
1n4148 x 2
.
The 1n4004 form a bridge rectifier.
The power supply is a 12V AC job.
These rectify the AC to DC.
It can also be powered with a DC battery.
But don't use a 12DC switchmode power supply
Its commonly used in radio receivers.
These coils can be bought to different specs.
Usually colour coded
In this project a black and 3 white are used.
The IF coil is also known as an inter-frequency transformer.
The basic characteristic of every coil is inductance.
Their inductance can be adjusted by stretching or squeezing the coil turns.
...The metal casing contains two coils.
The first coil on the left is connected to a capacitor forming an oscillator circuit.
The second coil transfers the signal to the next stage.
Install the voltage regulator.
Its a 7809 delivering 9V to the circuit.
final components... volume pot, power jack, switch, etc
.... first tests
The antenna.Volume plate.
...
connect speaker.
..
..
Tuning
The T1 reference coil doesn't need much adjustment.
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