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Adjustment
of Reverse warning device
If you finish the circuit assembling, you carry out fundamental confirmation such as no error of wiring, confirmation of power supply voltage etc.
After above confirmation is completed, the following point is adjusted.
Before turning on the power supply, VR3( volume adjustment ) turns to counterclockwise with the screwdriver( the volume to minimize ).
Adjustment of the volume
Turning VR3 with screwdriver the volume is adjusted.
The following adjustment is done with the sound of small at the time of the test.
After adjustment is completed, you install it to the car and adjust to the appropriate sound that you are surrounding of your car and hear.
Adjustment of oscillation frequency
Turning VR1 with screwdriver the height of the sound is adjusted.
Although the height of the sound is as you like, I think that a little low is good.
In the case of ear of a human, the place where is sending a high frequency sound( about 1KHz ) is recondite.
In the case of warning device, It is important that the place where is sending the sound( car that does reverse ) understands right away.
Adjustment of the change cycle of the sound
It is the adjustment of the repetition cycle of a high sound and low sound.
Fundamentally it needs not to adjust.
In the case that it adjusts it the value of C3 and C4 are changed.
The change cycle becomes short when the value small and become long when it enlarges.
In the case of the value of C3 and C4 is same, the interval of the high sound and low sound appearance is same.
The value of C3, C4, when it is too small, the change action will stop.
Adjustment of the tone quality
The signal that appears from SN7473 is rectangle wave (
).
Rectangle wave is including the comparatively high frequency component. When the people hear this sound with the speaker it is heard to the rasping sound.
Although even the rasping sound is good because it is a warning sound, the circuit of tone quality adjustment was attached.
The tone quality that you like is made with VR2.