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Help with 555 timers for drag race lights

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smithe30

New Member
Umm im having trouble picking a transistor here, I have some TIP31A transistors here, do you think those would work?
Also those decoupling capacitors you metioned before, are those needed and if so how do they fit into the picture?
Are the resistors still going to be 750Ohm with these transistors?
The protection diodes on the relays, will 1N4001 diodes work or would you suggest others?
Thank you very much.
 

MrDEB

Well-Known Member
Yes the tip31a should work

suggest breadboarding at least one then measure current to be sure instead of making smoke with the 4017
the capacitors are nothing special.
just a question?
I sure hope your NOT going to use this for street racing!!
use of the car battery makes me wonder.
 

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smithe30

New Member
Haha no, i'm building this because the lake that my friends and I race snowmobiles at has no power, and the arm-drop technique seems to cause too many problems. Thanks alot for your help.

My question now is where do i measure the current you were talking about in your last post?

Also will the 1N4001 diodes work by the relay coils?

Help much appriciated, thanks alot
 

MrDEB

Well-Known Member
bread board the transistor, base resistor, the relays, and the 1n4001 (I like 1n4148) all connected together.
then use an amp meter between the base resistor to 12v +
should be, according to ohms law 12volts / 750 ohms = 16ma.
need to double check the output of the 4017 on the data sheet.
the relay should close and transistor shouldn't get hot.
 

MrDEB

Well-Known Member
you can breadboard the base resistor, transistor, relay and diode now without the 4017.
If you have the 555 then wire it up and temp connect to base resistor (if the transistor/relay circuit works as planed and right amount of current.
building in blocks makes debugging much easier.
 

drback

New Member
I stumbled upon your postings by doing a web search. The project you are creating here is quite fascinating and I am trying to learn more about electronic circuits and how they function. I'd like to try building this circuit but have some questions. Once the circuit has been activated, how is it reset? Also, how is the time sequence between the lights controlled? If I'm thinking correctly, the time between each light is supposed to be .500 seconds?
 

Battleship

New Member
Why not substitute opto-isolator w/zero crossing trigger, TRIAC driver ICs for the relays? Then you can drop the applied source voltage for the entire circuit, and isolate the control aspect from the driver aspect, even to the extent that you can use 110vAC lighting if you like. Just an idea.
 

alec_t

Well-Known Member
Most Helpful Member
Why not substitute opto-isolator w/zero crossing trigger, TRIAC driver ICs for the relays?
This 2-year-old project is/was battery-powered :)
 
Last edited:

JCDes

New Member
Hello all, great forum you guys have here! I stumbled upon this because I need the exact same circuit. Is the circuit on post 22 the correct/working one? if not does anybody have one that will work with 12v lights also? Need to use a car battery since it is for mud 4-wheeler drag.
 

MrDEB

Well-Known Member
Its been so long since I built this thing. BUT I am no longer using it for cub scouts pinewood derby and the described unit is still in one piece along with added et timing. Works pretty good for a Drag Race Christmas Tree. IF you want a working unit I would be happy to sell the unit I have complete with Tree, lights, wires, set/reset buttons etc.
Make an offer.
 
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