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Anyone know how to make Dynamite sticks?

Dynamite Stick/ Sequential timer circuit help

Hello, I recently started working on these sequential tail light circuits for my car on a breadboard but have run into a problem. First off I have a 556 timer running in monostable mode with the inside light hooked up how it should be; directly to ground and positive of battery, and the outputs going into a TIP31AG mosfet (one per each side of the timer). I have the proper voltage going into the transistors from the outputs of the 556 and the lights are lighting as they should but there is no sequencing. I am using the schematic from http://www.gofastforless.com/electrical/lights.htm

Also I am using 100k pots

EX.
1 I apply power to 556
2 Proper voltage is sent from 556 outputs to transistors
3 Transistor switches on the light
4 Both bulbs light at the same time and then stay on
5 No sequence

Any help please get back to me, thanks
 
From you description, it sounds like there is some delay from bulb #1 lighting to the bulbs controlled by the mosfets lighting. Correct?

Double check all connections, and especially check the hookup of the 100k pots. Make sure they are set so the resistance changes when the shaft is moved. Pots vary greatly in thier hook up.

Also, the TIP31AG is a bipolar transistor, not a mosfet. The TIP31 also has only a 3A rating, and some stop light bulbs are darn close to that. I would suggest switching to mosfets, as they will not require as large a heatsink nor require as large a drive from the 556 (thereby reducing heat). At least a 10A rating is needed for running incandescent stop lamps IMO.
 
I'm not really sure what is going on, but I just put in two IRF510 mosfets in place of the bipolar transistors and they light them up but the same problem is happening. No sequence at all. I'm using square blue 100k pots with the little screw area on top. How exactly do you have yours wired up because I saw your circuit board pic and can't tell where the wires go?

thanks for helpin by the way..hope i dont ask too many questions
 
Put your ohm meter across two terminals on the pot. Move the screw and see if the resistance changes. If not. try another combo. You need them wired across two terminals that adjust. It sounds like you have them wired across the constant 100k rather than the adjustable side, since they both time out the same. It's pretty unlikely they are both adjusted EXACTLY the same.

If you don't have an ohm meter, you'll have to find the pin out diagram for the pots.
 
Exactly like the gofastforless, except I used the mosfets instead of relays. here's my crappy adaptation of the schematic on the gofastforless site:

275_20_11_09_3_57_09.jpg
 
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well i started from scratch again on my breadboard making it just like the gofastforless schematic shows and when i hook power to it, all three LEDs light up at once and stay on..and thats even without a potentiometer in place between the pins 1&2 and 12&13 to power..I put a 100k resistor in place of where the pots are suppose to go and when i apply power, all the lights come on at once and then lights 2&3 stop lighting at the same time..i've checked all my connections several times..any advice??
 
The good news: your timer circuit is working. If you had the pots in you could adjust the lights to go out at different times.
The bad news: You put a N channel MOSFET (IRF510) in the circuit. I missed that detail before. To make the lights come on when the time flips, you need a P channel MOSFET. I used the STP12PF06, but there are lots of good P channel MOSFETS outthere now. You want one with low 'on' resistance, .2 ohms or less.
 
ok I haven't gotten the P channel MOSFETS yet, getting them in the morning. Anyways I hooked up the circuit with the n channels to my battery charger that puts out a constant 10v, and the lights just flicker or don't light at all. It acts like the current is too big. When I have it hooked up to 6v it works perfect. Is there an easy solution to this? It might be because the battery charger is pulling more amps than a regular car battery?
 
Battery chargers are terrible power supplies. They put out a poorly regulated current with LOTS of noise. In addition, under light load, they often have huge voltage swings (too quick to show on most voltmeters). Hook it to your car battery, that will give you a good 12V source.
 
You're making a Flux capacitor?

I'm sure it will end up looking like the electrical refiguration of the Flux capacitor on the Back the Future car! :thu

20090615-back-to-the-future.jpg
 
Ok I hooked her up to my car battery and it worked fine. I picked up some diodes today, part # 276-1661, and tried to order some STP12PF06 MOSFETS from Radiosh!t, but they can't order them :rant Looks like I'll get em off the internet and have to wait even longer...
 
Yeah I've bout some 250k and 500k pots from Mouser, but that ended up causing an overdraft on my account. Newark is the place on google that has the STP12PF06 MOSFETS pretty cheap.
 
BTW, even with a low on resistance MOSFET like the STP12 series, you'll need a heatsink if you use bulbs (I use LEDS). The heatsink will ensure longevity in the auto environment.
 
ok thanks good to know..is there a certain type that i need or will just any heatsink do the job? Also I'm not even sure how exactly you use them.
 
"shaggycowboy09" said:
ok thanks good to know..is there a certain type that i need or will just any heatsink do the job? Also I'm not even sure how exactly you use them.
Click to expand...

A 2 x 2 inch square of aluminum is likely enough. They should not get much hotter than you can touch when operating.

They have to be electrically isolated, either from the MOSFETS (there is a mounting kit) or from anyother surface if not isolated from the MOSFETs. I usually just mount them using the kits (usually available at RS). You need to use heat sink compound, also available at RS (although expensive, so consider ordering with the MOSFETs)
 
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