Anyone know how to make Dynamite sticks?

[Rubedizzle]

Hey There,

I should probably clarify this is being hooked up OUTSIDE of the car, to a constant 12V source, not to an electronic or mechanical flasher. Therefore #1 should be staying on, and so should #2 and #3 (there should be no flicker whatsoever, nor should the pattern of #2 on - #3 off or vice versa be going on).

It should turn sequence as such:

#1 on #2 off #3 off
#1 on #2 on #3 off
#1 on #2 on #3 on

and then stay like that until power is reset (by a flasher) or in the case of pushing on the brakes, i let off the brakes.

Sorry, I should've clarified there was no flasher in my current set up, it should function correctly however the way it is hooked up!

Thanks for the response, any more help is greatly appreciated.

[gotstang]

My knee-jerk reaction is that your problem is the lack of a flasher. The flasher unit effectively applies and removes power to the timer IC, resetting it. With the flasher in place, it should function same as the original.

So, after *briefly* turning my brain back on, it looks like you're on the right track in the post above. :lol

I bet if you switched your power supply off/on every second or so (half-arse simulating a flasher) it will work fine. I dunno about replacing the pots with resistors though, this circuit seems sensitive enough to variances that the 5% tolerance of the resistor could have both sides flashing at different rates. I kicked around the same idea and decided to stick with the pots for safety's sake.

[Rubedizzle]

Hey There,

Thanks for the reply. Well that doesn't seem to work, as the capacitors i believe still contain some energy, so if i shut it off and quickly turn it back on,  the led's light up with a shorter inital delay then they should, as the capacitors haven't been drained.

I originally built it with 100k pot's and then switched to resistors just to see if that helped. Unfortunately it will not work if hooked up to a flasher, as they are not acting sequentially, lights 2 and 3 are flickering back and fourth. Furthermore, that means if I hooked this up and pushed on the brakes, my brakes would be flashing.....and you see where i am going there.

Did you make any modifications to the design at all? I have followed the final schematic, and will be taking a picture of the parts in the next day or so to show what I am using

Thanks again!

[apollard]

Hey Folks,

Hate to resurrect an old thread - just attempted this for my self. I built it out on a breadboard ahead of time, and am testing it using some 12V led's currently (although I will be using halogen reverse lights). I have followed the perfected schematic, and am having a weird situation occur, which you might be able to help me figure out.

I am using the 556 timer as stated, and what happens is when I provide power, my #1 light (which is not involved in timing at all) turns on as normally, and there is a delay in 2nd light powering on, and then the 3rd and 2nd lights occilate on and off (when 2nd is on, 3rd is off, when 3rd is on, 2nd is off), and they continue to flash like this, although the power source is constant. I hooked up only half of the circuit (so using one half of the 556 - so it acted as a single 555 timer) and the light being powered comes on as it should, with the delay set by the 100k pot i have used. I have played with the pots, and i have also replaced the pots with 100k resistors, same issue! The pots are changing the timing, however the lights should not be flicking off and on, as the power source is constant.

I've attached a video, please check it out so you can see what is happening, and maybe you can help me figure this out before i build this on a circuitboard.

Thanks folks!

-Mark

Your timer is running in astable mode. 555 timers can run in one-shot or astable mode. Astable mode is an oscillator - just like your lights are doing. To run the light sequence correctly, you need one shot (ie, the timer runs the timing once, and holds the lights on until the power goes off). More info here:
http://www.sentex.ca/~mec1995/gadgets/555/555.html

Quadruple check everything - it's easy to get a wrong connection on a breadboard, or wires touching. It's also possible that you have some feedback due to inductive coupling (especially if you used cmos versions of the 556). If all else fails, tear it apart and build it again - but route the components differently.

[Rubedizzle]

Well I think i figured it out - There is an error in the schematic posted by gotstang:

The reset pins of the 556 should not be directly connected to +12V, but instead should be connected to the 1K resister for each mosfet - Between the 556 timer and the resister. This allows the timer to run in monostable mode - hence resolving the issue I had.

Here is a diagram of a 555 (556 is two 555 timers together), and shows what i am talking about, and how I figured it out.

Will let you know how it all turns out after it's soldered up and installed!

[tarafied1]

I wish I knew what I was looking at... I just went ahead and bought some $120+ Dynamite sticks

[shaggycowboy09]

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

[apollard]

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.

[shaggycowboy09]

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

[apollard]

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.

[shaggycowboy09]

I don't have an ohm meter so I'll get one today after work.  Did you wire everything up just like the fastforless schematic?

[apollard]

Exactly like the gofastforless, except I used the mosfets instead of relays. here's my crappy adaptation of the schematic on the gofastforless site:

[shaggycowboy09]

thanks apollard for all the help..i'll give this a try and see what happens

[shaggycowboy09]

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??

[apollard]

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.

[shaggycowboy09]

you are a beast apollard 
It makes sense to me now..I'll have to get some of those P channel MOSFETS and fire this baby up..thanks

[shaggycowboy09]

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?

[apollard]

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.

[Dne']

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

[shaggycowboy09]

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    Looks like I'll get em off the internet and have to wait even longer...

[apollard]

Radioshack is useless for parts now. I generally order from Newark.

[shaggycowboy09]

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.

[apollard]

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.

[shaggycowboy09]

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.

[apollard]

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.

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)