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Flash 3 x per second then stay static help!

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slinkyslink

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Hi All,

First thing, hello I’m new to this forum and have picked this up as part of a recent hobby. I thought that this was a good place to start in making circuitry to improve my skills.

I’ve completed some elementary research and have so far designed my first circuit for a project that I’m eager to get underway.

I'm using Circuit Wizard to; design, test, print and catalogue components.

Scope
Design a circuit that can plug into a lighting array which is triggered by push to make switch, the lights must flash at least 3 times rapidly then stay static until the switch is released.

Budget
£10-£15 for components.
All tools available

Risk
Me & anything electronic.
Current Issue
Lights are not receiving any power.
Current Design

**broken link removed**


Can someone please look over my circuit and let me know where I’m going wrong please, i want to go buying and making
!

Happy holidays,
James
 

What happens so far?
You should get the LED and light to come on by closing SW1 and SW2.
If that works, try temporarily disconnecting the top of the LED from Q2 and connect it to pin 4 of IC2 instead. When you close SW1 the LED should light for the duration of three flashes then go out and stay out. The LED should not itself flash, you are just using it to monitor the time 'window' that lets IC2 do the flashing.

Brian.
 
Hi Brian,

Many thanks for your reply - When I depress SW1 nothing happens :-(.

This is what should be happening -

The circuit uses two 555 timer chips. One chip (IC2) operates in the multi-vibrator
mode and oscillates at about 3 pulses per second; this drives a Power
MOSFET switch in series with the bulb light wiring. The length of the
flashing period is set by the second 555 timer (IC1) operating in a monostable
mode, as a one shot. This chip disables the oscillations of the
multi-vibrator chip after a period of 1-1/2 to 2 seconds. The flashing cycle
is repeated each time the SW1 is released and then pushed again.

SW2! is installed so that in the event of a circuit failure, the circuit can by
bypassed with the flip of a switch; no need to disconnect the whole circuit
board. LED1 was incorporated and is directly across the brake lights. This LED
monitors circuit operation.

I don't know if it is Circuit Wizard not working correctly, but I will certainly try your recommendations and will get back to you with the results.

Regards,

James
 

An alternative circuit. Used for ~10 years.

Ken
 

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  • BrakeLight01.gif
    BrakeLight01.gif
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Hi Ken,

First thing is many thanks for your reply and providing me that circuit diagram, I’ve just built it in the Circuit Wizard and it works and i think i understand which is also a bonus, I’m learning!
The only thing i want to add to this is to make the bulb stay static after N amount of flashes.

Would I use a capacitor to release a charge to then trigger another NAND component to then flip a transistor to keep the bulb static?

Once again thank you all for your replies, once built i shall upload the project for others to use going forward.

Many thanks,

James
 

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