This scheme was created to model fire engine in the UK. I saw her a long time ago in a magazine. It was very interesting to collect and test it. Which I did. operating circuit. Checked!
Description
The scheme is based on the CD4093 chips, which consists of four Schmitt triggers (IC1). It is the analogue of well-known domestic IC K561TL1. Structurally it consists of 4 logic element "2I-NO". Technical parameters of the chip and its pinout, you can explore any figures below.
Switching blue lights flashing occurs at a low frequency which is generated by the generator to IC1a.
Its output signal controls the NPN-transistor TR2, through a current limiting resistor R4, and which includes a LED D2, and IC1b inverted signal simultaneously controls the NPN-transistor TR1 through a current limiting resistor R2, comprising LED D1.
Resistors R3 and R5 470 ohms, are used to limit the current supplied to the diodes D1 and D2.
LEDs flash in opposite phase. Conclusions IC1a and IC1b used to control the sound generator on and IC1c IC1d, generates two different frequencies.
Piezo WD1, included on the generator output, outputs a sound signal simulating traditional UK dual tone siren.
Battery B1 has to be alkaline or rechargeable 9V, because current consumption is relatively high. S1 - sliding the slide switch, which is located in the rear of the vehicle. Additional speaker set optionally.
The circuit still in use:
- C1 - polar capacitor - 10 uF;
- C2 - a non-polar capacitor - 10 nF;
- C3 - Capacitor nonpolar - 150 nF.
- R1 - resistor - 120 ohms;
- R6 - resistor - 180 ohms;
- R7 - resistor - 22 ohms.
Chains R1-C1, R6-C2 and R7-C3 are used to set the desired pulse frequency.