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Parts list
of Reverse warning device

Symbol	Name	Description	Remarks
IC1	NE555V	Timer IC	Note 1
IC2	SN7473	Dual JK-FFs with Clear	Note
IC3	SN7400	Quad 2 Input NAND	Note
IC4	SN7473	Dual JK-FFs with Clear	Note
IC5	SN7400	Quad 2 Input NAND	Note
IC6	µPC575C2	2W Low freq elec power amp	Note 2
IC7	78L005	3 terminals voltage regulator (5V)	Note
TR1	2SC732	Transistor	Note 3
D1	1S1588	Diode	Note
D2	1S1588
R1	22K ohm	1/8W	Note
R2	4.7K ohm
R3	1K ohm
R4	1K ohm
R5	22K ohm
R6	8.2K ohm
R7	5.6K ohm
R8	5.6K ohm
R9	22K ohm
R10	47K ohm
R11	150K ohm
R12	120K ohm
C1	0.01 µF	Multilayer ceramic capacitor	Note
C2	0.01 µF	Multilayer ceramic capacitor
C3	470 µF	Electrolytic cpacitor(10V)
C4	470 µF	Electrolytic cpacitor(10V)
C5	0.022 µF	Polyester film capacitor
C6	2.2 µF	Electrolytic cpacitor(16V)
C7	47 µF	Electrolytic cpacitor(16V)
C8	100 µF	Electrolytic cpacitor(16V)
C9	47 µF	Electrolytic cpacitor(16V)
C10	470 µF	Electrolytic cpacitor(16V)
C11	0.22 µF	Polyester film capacitor
C12	100 pF	Multilayer ceramic capacitor
C13	0.01 µF	Multilayer ceramic capacitor
C14	100 µF	Electrolytic cpacitor(16V)
C15	100 µF	Electrolytic cpacitor(16V)
C16	0.01 µF	Multilayer ceramic capacitor
VR1	20K ohm	Variable resistor of half fixation	Note
VR2	10K ohm
VR3	100K ohm
SP	Speaker	2 watts output ( Waterproof style )	Note 4
	Printed board	30 x 25 holes universal PWB	Note
	0.32mm wire	Tin coated wire of diameter 0.32 mm	Note
	Case	As you like
	Twisted wire	Red, Black, White, Blue (1m long)
	Bush	Buffer of the case and wiring
	Spacer	3mm(Hole diam) x 5mm(Long) x 4 To attach the circuit to the case
	Screw, Nut	3mm(Diam) x 10mm(Long) x 4

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Note 1 (NE555)

Pin arrangement
This IC has both of trigger terminal and reset terminal for wide area application that is a-stable or mono-stable multivibrator etc.

Power supply voltage range : 4.5V to 16V
Maximum frequency : 500KHz
Temperature drift : 0.005%/°C
Max output current: 200mA
Delay time setting : several micro seconds to several hours
Duty cycle is able to be adjusted
Output compatible TTL

A-stable oscillation circuit

Calculation of output frequency

Time when output is High Level

TH = 0.67 (RA + RB) x C

Time when output is Low Level

TL = 0.67 x RB x C


Calculation example 1
( RA = 22K-ohm, RB=4.7K-ohm, C=0.01 µF ) [ VR1 minimum ]

TH = 0.67 x ( 22 x 10³ + 4.7 x 10³ ) x 0.01 x 10^-6

= 0.67 x 26.7 x 10^-5
= 178.8 x 10^-6
= 178.8 micro sec

TL = 0.67 x 4.7 x 10³ x 0.01 x 10^-6

= 31.5 x 10^-6
= 31.5 micro sec


f = 1 / TH + TL

= 1 / ( 178.8 + 31.5 ) x 10^-6
= 4754 Hz


Calculation example 2
(RA = 22K-ohm, RB = 24.7K-ohm, C = 0.01 µF ) [ VR1 maximum ]

TH = 0.67 x ( 22 x 10³ + 24.7 x 10³ ) x 0.01 x 10^-6

= 312.9 micro sec

TL = 0.67 x 24.7 x 10³ x 0.01 x 10^-6

= 165.5 micro sec


f = 1 / ( 312.9 + 165.5 ) x 10^-6

= 2090 Hz


If you request only frequency it is OK with f = 1.49 / ( RA + 2RB )C .

The sound that appears from the speaker high-pitched tone beomes 1/4, low-pitched tone becomes 1/8 of these frequency.
In the case that VR1 is minimum value the sound of about 1200Hz and 600Hz appear alternately.
In the case that VR1 is a maximum value the sound of about 500Hz and 250Hz appear alternately.

Note 2 ( µPC575C2 )

This IC was developed for the use of voice electric power amplification such as the small size stereo that installs to the car.

Maximum rating ( Ta = 25°C )

Vcc : 17V ( operating )
Icc ( peak ) : 1A
PT : 1.9W ( 30mm x 30mm copper sheet is used for radiation )
Topt : -20 to +75°C
Tstg : -40 to +150°C

Note 3 ( 2SC732 )

It is possible use even 2SC1815 etc.

Pin arrangement is the same as 2SC1815.

Note 4 Speaker

This time things of 2 watts was used. I think that it has no problem be small a little more.
You need to be careful so as not to become noise.
The big sound is not necessary, because it is such a thing that warns to the person who is behind a car.
The size of the speaker selects after the attachment position to the car is decided.
Although I wrote as the waterproof style in the parts list, what I am using is not waterproof style. I am inserting the speaker in a thin vinyl bag to make waterproof.
Devise the installation method of the speaker by the kind of your car.