[Menu]>[Application]>[Circuit Idea for the Car]>[Thief warning]>[Production]

Adjustment
of Thief warning device


The +12-V power unit and the FM radio are necessary to adjust.

Is there not mistaking in the installation of the part?
Attempt to confirm once again.

---

The original power supply is supplied through the point of tact of RL1. Because to work RL1 in the adjustment is troublesome, the power supply is directly connected with the side of the output of the RL1 point of tact.
Connect the +12-V power supply with the side of the positive of C15.
The side of the negative connects with the side of the negative of C15.

Connect the vinyl covered wire with the 1-m length with the side of the output of L3 and it places near the FM radio.

Turn on the power of the thief warning device.
Adjust the frequency of the FM radio to 9 times of frequency of the crystal oscillator (Xtal).
In the case of me, the frequency of the crystal oscillator is 9.8403 MHz, then the frequency of the electric wave becomes 88.5627 MHz.
When the FM radio receives the electric wave of the thief warning device, you can hear the music.
When you are not possible to hear, confirm the circuits such as the installation of the part once again.
It is better if there is an FM radio which has the meter which displays the strength of the electric wave to be receiving. Because the ordinariness isn't installed, it adjusts while hearing with the ear.

Adjust L2 first. Adjust the coil of L2 with the screwdriver that it is possible to hear the music clearly.
There should be a screwdriver of the adjustment exclusive use but if not being, it uses the screwdriver which is made from the ordinary metal.
When the FM radio is receiving the strong electric wave, the change can not be recognized even if it adjusts the coil. In the case, remove the antenna of the transmitter or separate the transmitter from the FM receiver. The adjustment is easier in the condition which a little noise enters.

Next, adjust the coil of L3 for the music to become big in the same way.
After that, adjust L2 and L3 alternately and the electric wave makes become the strongest.

If being the FM radio which has the meter which shows the reception condition, adjust for the electric wave to become strong.

In the kind of L2 or L3, they can not be adjusted to the appropriate frequency.
In case of the condition of L2 that the peak point with the strength of the electric wave removed the core (the control screw), the value of C10 is too big. Exchange in the one with the a little small capacity.(Ex.39pF)
In case of the condition that the peak point centered the core, it makes C10 the a little big one.
Probably, I think that it is the range of several pF or tens of pF.
In case of L3, change the value of C12.

Above, the adjustment is the end.