Motorcycle Flasher Circuit validation

Thread Starter

joe_echo

Joined Oct 4, 2023
24
Come up with an issue now that the pcbs have been made. My 555 timer isn't outputting a pulse instead is a constant 12v.

Any ideas?
 

sghioto

Joined Dec 31, 2017
8,634
Solder short on the board somewhere or board not configured correctly.
Post a photo of the board to maybe see if the configuration is correct.
 

sghioto

Joined Dec 31, 2017
8,634
Remove R2 or connect from pin3 to 12volts.
Don't need that large of a capacitor either. Change R1 to 47K and C2 to 47uf.
 
Last edited:

Thread Starter

joe_echo

Joined Oct 4, 2023
24
Breadboarded it works as expected but when soldered to the PCB the transistor is at a permanent 12v. Attached are the board and the schematic.

Values were corrected as per previous posts
R1=100K
R2=10K
R3=10K
R4=750
C1=10nF
c2=100nf (filtering)
C3=47uF

PNP can handle 600mA

Output from flasher pnp will go to switchgear to be switched to the correct indicator side.
SW1 and SW2 are purely to turn on the relay coil by switching it to ground.

1740598931104.png
1740598995624.png
 
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