The 100 Ohm pull-down resistor you added on the first 555 won't be needed when the circuit is finally installed in the car, since for now it's acting in place of the unlocking motor resistance.

Thanks for clarifying that point. I suspected something like that might be true, but was not at all sure.

 

OK, made some progress again today. Thanks also to everyone in this thread.

This is where I'm at, in picture form. (video below)

I ran the trigger wire (pin 3) out to a blank row with a 1u cap, and a 100k resistor in a row below it, then ran that over to the gate on the NPN transistor. The negative from the transistor (weird to me, how NPN works, considering I've only experienced relays to transfer a positive signal) goes to the ground on the small 12V SPDT relay. The Vcc to the relay comes from the 9V (for testing).

The separate power rail for the incandescent bulb goes through the relay and is switched out to the bulb. The incandescent bulb is the same type as the car has, or similar. I tried doing this on the 9V but there's not enough current/juice to power everything.

I also need to add another relay in "front" of everything that only powers the 555 when the car is off. When the car is running, it will disable this whole circuit, so that when I unlock the doors with the manual power switch, the lights don't flash. Do I need any special resistors in "front" of the trigger wire for that?
Here's video

 

Well, now I'm confused. I thought I understood how the circuit would work, but I'm missing something here. I don't see D1 or D4, nor any other way for this circuit to be generating two blinks, and yet that's clearly happening.

...And now that I've looked more clearly at the pic, it looks like this circuit is an interesting departure from the plan. The 555 nearest the camera is the one receiving the initial start signal, and it's the one whose output drives the MOSFET/relay/light circuit.

It's hard to tell from the angle of the photo, but it looks like there's no signal to the input of the top 555, and it looks like the top 555's output feeds into the input circuits of the bottom 555.

I must be seeing something wrong and/or over-thinking this, cause it seems to me like there shouldn't be double blinks here, and the only explanation I can think of to explain how it might generate double blinks is too zany to repeat without more to go on!

 

OK, made some progress again today. Thanks also to everyone in this thread.

This is where I'm at, in picture form. (video below)

I ran the trigger wire (pin 3) out to a blank row with a 1u cap, and a 100k resistor in a row below it, then ran that over to the gate on the NPN transistor. The negative from the transistor (weird to me, how NPN works, considering I've only experienced relays to transfer a positive signal) goes to the ground on the small 12V SPDT relay. The Vcc to the relay comes from the 9V (for testing).

The separate power rail for the incandescent bulb goes through the relay and is switched out to the bulb. The incandescent bulb is the same type as the car has, or similar. I tried doing this on the 9V but there's not enough current/juice to power everything.

I also need to add another relay in "front" of everything that only powers the 555 when the car is off. When the car is running, it will disable this whole circuit, so that when I unlock the doors with the manual power switch, the lights don't flash. Do I need any special resistors in "front" of the trigger wire for that?
Here's video

The additional relay should be pretty easy. Just wire the coil of an automotive relay into some switched power in the car (stereo wiring or maybe cigarette lighter wiring.) Then wire the normally-closed contacts to unswitched 12V and to the new circuit. As long as you're using a relay with a 12V coil and tapping the switched power from somewhere with a little power to spare, you should be fine without extra resistors, etc.

 

I don't see D1 or D4, nor any other way for this circuit to be generating two blinks, and yet that's clearly happening.

I agree with Ebeowulf17.
If you don't follow the posted circuit, fine; but it makes it very difficult for us to help with any problem you might be having.
You're missing D5. Without that across the relay coil the FET (not 'NPN') is unlikely to survive long.

 

I agree with Ebeowulf17.
If you don't follow the posted circuit, fine; but it makes it very difficult for us to help with any problem you might be having.
You're missing D5. Without that across the relay coil the FET (not 'NPN') is unlikely to survive long.

Oh, yeah! I got so distracted by the new circuit that I forgot about D5, which is definitely not optional!

I'd be interested in seeing a few more angles of this board so I can accurately read the whole layout. If it's doing what I suspect it's doing right now, it won't work with the whole thing running on car power.

 

OK, a few things to cover here.

Alec - I had to chuckle a bit, because you're giving me more credit than I deserve. I'm definitely not ingenious enough to NOT follow the schematic and come up with my own design. If it's incorrect, it's because I didn't do something right, not because I defiantly opposed your design. I'm trying my best.

ebeowulf - I mentioned this problem a few posts back and maybe it was overlooked. I had already mentioned that the light didn't blink twice off of the first 555. It only blinked twice from the second. The output pin (pin 3) of the first 555 goes to the input pin of the second (pin 2) as shown in the schematic - correct? I'll post another picture of the board below.

As for the diodes through the TVS and the MOSFET - the power to the bulb was done on another rail with a 12V motorcycle battery so it was isolated from the breadboard, so just for my testing there shouldn't have been any issue - is that correct?

Pictures (overview)

First 555

Second:

MOSFET (at the time I just had the LED hooked up, not the relay with the incandescent)

Side angle w/ flash

 

Does radio shack even exist anymore?

I would consider Digikey if I were you, Its where we bought all our components in school building op amps and what not.

 

OK, a few things to cover here.

Alec - I had to chuckle a bit, because you're giving me more credit than I deserve. I'm definitely not ingenious enough to NOT follow the schematic and come up with my own design. If it's incorrect, it's because I didn't do something right, not because I defiantly opposed your design. I'm trying my best.

ebeowulf - I mentioned this problem a few posts back and maybe it was overlooked. I had already mentioned that the light didn't blink twice off of the first 555. It only blinked twice from the second. The output pin (pin 3) of the first 555 goes to the input pin of the second (pin 2) as shown in the schematic - correct? I'll post another picture of the board below.

As for the diodes through the TVS and the MOSFET - the power to the bulb was done on another rail with a 12V motorcycle battery so it was isolated from the breadboard, so just for my testing there shouldn't have been any issue - is that correct?

Pictures (overview)

First 555

Second:

MOSFET (at the time I just had the LED hooked up, not the relay with the incandescent)

Side angle w/ flash

Thanks for the pics! Starting work now, but I'll take a better look as soon as I get a chance. Two quick points:

The tvs can certainly wait, but the diode that is shown wired in parallel with the relay should definitely be used any time you're using the relay. When relays turn off they create reverse voltage that can wreak havoc. The diode is there to give that voltage a way to dissipate safely instead of destroying all your valuable components.

As I tried to explain earlier, perhaps not clearly, the circuit up to the point we've gotten it so far should NOT be blinking twice yet. One timer should create a delay (a certain amount of dead time with no lights lit) after which the second timer lights the output briefly. The first pulse of light, as you yourself described much earlier in this thread will come directly from the original input signal (not from either 555) and since we haven't wired the connections yet to make that happen, we shouldn't expect to see two blinks yet.

Try moving your trigger wire back to the top 555 where it belongs. That should probably get us back to seeing one blink instead of two. When you test this, tell me if there's a delay before the blink or if it blinks immediately upon release of your start signal. If there's a delay before the blink, everything is working perfectly and it would be time to add those couple other diodes I mentioned a few posts back.

 

Trigger wire back to the first 555 has a short delay, then the light fires, yes. Will add diode now.

 

ARG. Very frustrated! I don't understand how the diagram shows the resistors coming from the input trigger of the 555's going to the positive rail, but on my breadboard they are going to negative!?

I added the diodes, but then I noticed the light wouldn't turn off. The 1u cap by the MOSFET caused this, so I moved it inline (same row) with the pin from the MOSFET, but I don't know if that's right either. Previously it had one pin going to ground on the side rail. This is visible in picture #3. Note the cap is inline with the first pin of the FEt. Is that right?

Here are 4 more pictures. Note I moved the LED down and made the wires shorter so they are less of a distraction. The light now triggers from the first pulse ( which = me touching the jumper) then has a delay then pulses again. The jumper row meant to be the +12V unlock pulse, is the first row A1 which has two diodes - one goes down to the FET, and the other goes to the trigger of the first 555.

side

 

I had to chuckle a bit

Good . That helps to overcome the frustrations!

I had already mentioned that the light didn't blink twice off of the first 555. It only blinked twice from the second.

Neither I nor Ebeowulf17 know how you managed that. The idea is that :-
the unlocking 12V pulse trailing triggers the first 555 but is also fed via D1 to the FET gate to cause the first blink,
the first 555 introduces a delay and then triggers the second 555,
the second 555 output is fed via D4 to initiate the second blink.

 

I don't understand how the diagram shows the resistors coming from the input trigger of the 555's going to the positive rail,

R1 and R4 are called 'pull-up' resistors. Their purpose is to hold the trigger input pin 2 at the +ve supply voltage except when the brief trigger pulse is actually being applied. Remember, pin 2 needs to be pulled low (towards 0V) to trigger a 555. If it were held permanently low the 555 would not time out.

 

So should the other end of R1 go to the positive or ground rail? It works when it's on the negative rail, but if I put it on the positive rail nothing works.

Alec_t is there a way for us to exchange contact information outside of here? I need to ask you about the circuit ownership. I can't PM you for some reason.

 

Trigger wire back to the first 555 has a short delay, then the light fires, yes. Will add diode now.

That is excellent news. Congrats!

 

R1 and R4 are called 'pull-up' resistors. Their purpose is to hold the trigger input pin 2 at the +ve supply voltage except when the brief trigger pulse is actually being applied. Remember, pin 2 needs to be pulled low (towards 0V) to trigger a 555. If it were held permanently low the 555 would not time out.

I'm guessing the confusion here is because we now have the extra resistors on the breadboard that weren't part of the original schematic. The breadboard still includes the proper pull-up resistors on trigger inputs (pin 2.) We've also temporarily added pull-down resistors, but they aren't on the 555 triggers. They're on the other side of the capacitors (and in fact, we should only need the one on the first 555, not the second.)

 

Where can I find a smbj24ca? I see them sold in 50 packs on Amzon and eB. I only need 1 and radio shack doesn't carry them.

That's right about the pulldown. Forgot. Is there anything wrong with leaving it on there?

One more question - I have a 16v 220u cap, but I think the sheet says 25V. Is the 16V OK to use? Or should I go back to Radio Shack and try to find a 25V?

Also, how do I get this from PCB into a plastic housing with fuse breaker inputs and outputs? I want a little ABS black box for it, similar to something like this, obviously without 50 wires, I would have 2-3 wires. I'm just asking how to get it from breadboard to a little module/housing/box?

 

Where can I find a smbj24ca? I see them sold in 50 packs on Amzon and eB. I only need 1 and radio shack doesn't carry them.

DigiKey and Mouser are my two favorite sources for almost any electronic components. I personally prefer the Mouser website and search functions slightly, but in my area shipping is usually half the price on DigiKey, plus they seem to have obscure stuff I need more often than Mouser, so I end up using DigiKey quite a bit more. Either one is a great resource.

 

Also, how do I get this from PCB into a plastic housing with fuse breaker inputs and outputs? I want a little ABS black box for it, similar to something like this, obviously without 50 wires, I would have 2-3 wires. I'm just asking how to get it from breadboard to a little module/housing/box?

Entire books could be written on this subject, so I'm not sure I can give you a great, simple answer, but I do have one recommendation for making a more permanent version of the circuit (although they are a bit pricy.) I really like using "perma-proto" boards from Adafruit. They are laid out exactly like breadboards, but with pads for soldering so you can make permanent, reliable connections. The matching layout makes it easier to copy circuits over. There are much cheaper prototyping pcbs available, but I just happen to like the quality and convenience of these. They come in a variety of sizes. Which one you need just depends on how compact you can make your layout without losing functionality. I suspect this project could get down to a "half size" board, but it might need "full."
http://www.adafruit.com/products/591

 

That's right about the pulldown. Forgot. Is there anything wrong with leaving it on there?

The pull down on the second 555 is definitely a total waste and can be eliminated right away. The pull down on the first 555 is kind of a power hog right now. If you have a variety of resistors around, try some slightly higher values, say between 1k and 5k. I tend to think Alec is right that it's unnecessary when connected to the car, but if the whole thing works with a higher resistance value, it'd be pretty harmless to leave the higher value pull down in that part of the circuit.