I have several of these old buzzers in the garage and would like to wire one in my 49 Ford to keep me from leaving my headlights lights on. The positive feed is easy enough but the negative side I can't figure out. Anybody know the skinny?

 

it would seem simple enough to me to have a relay controlled by the ignition switch, say you control the relay off the ignition circuit. ground to the "common" terminal, and the NC (normally closed/on) terminal running to the buzzer. turning the key on will then open (turn off) that circuit.
and of course, positive side of the buzzer to the parking lights

 

Run the + side of the buzzer to a diode you can get from radio shack. It will hook to the side of the diode that has the stripe. Run the other side of the diode(the no stripe side) to the headlamp power(dimmer switch would be a easy spot to pick this up).

Run the negative side of the buzzer to a 12v source that is hot when the key is in run. This can be picked up in the fuse box.

When the key is on, and the headlights are on, there is 12v on both sides of the buzzer, and it will not buzz. As soon as you turn the key off, but the headlights are still on, there will be headlight power on one side, but nothing on the other side, and power will flow through the diode, through the buzzer making it buzz, and then find a ground in the dead ignition circuit somewhere.

If you have the ignition key on, but the headlights off, power will try to flow from the negative through the buzzer, toward the dead headlight circuit, but the diode will block the flow of current and the buzzer will not buzz.

 

Is there not a source where I can wire the positive side that doesn't require a relay or a diode? I was hoping to hook this up from parts I already have. I'm not electrically inclined...

 

not that i'm aware of. maybe somewhere on a computerized vehicle, but not on your 49.
wiring it up is really pretty simple. i play with relays all the time, they're quick and simple to wire up. i haven't played with diodes much, but they're also pretty simple, but they usually require a soldering iron to install.
don't be afraid of electrical stuff, but make sure you do it well

 

I'm totally lost on diodes but I have worked with relays some. I have some old horn relays. Would a horn relay work?

 

i don't think the horn relay would work. what you want is one of the standard 5-pin relays you find in just about every modern car. these Amazon.com: Absolute RLS125 12-VCD Automotive Relay SPDT 30/40A: Car Electronics
every parts store has them in stock, along with sockets they plug into. they're cheap, universal, and reliable.

 

Thanks, I have a 5 pin relay. Can you tell me how each of the 5 pins would be wired to the buzzer?

 

terminals labeled "85" and "86" are the control circuit, one of those goes to ground, the other to something hot with the key on.
the remaining terminals are labeled "87", "87a", and "30". if i remember right, 87 is common, 87a is NO, and 30 is NC. thats working from memory, so you might want to verify that. in any case, the common terminal (i believe 87) goes to ground, and the NC terminal (i believe 30) goes to the noisemaker you intend to power

 

85 - GND
86 - 12V Ign on
87- GND
87A- NO?????
30- Buzzer

Okay, lets do it this way:

A - 12V switched power - 86
B - Battery Ground - 85
C- 12V Power when light switch is on - 87A?
D - Power to buzzer - 30
E - Ground to buzzer - 87?

Is this correct? Sorry you're dealing with an electrical moron...

 

ok, to clarify abbreviations above:
NC = "normally closed" (closed = on)
NO = "normally open" (open = off)
and i just ran outside and checked while thinking about this, and I GOT THINGS BACKWARDS on the last post. the actual order of posts on the relay is
85, 86 - control circuit (one +, one -)
30=common
87=NO
87a=NC


A - 12V switched power - 86
B - Battery Ground - 85
C- 12V Power when light switch is on - wire directly to buzzer (+)
D - to buzzer ground - 30
E - battery Ground - 87a

in other words, the relay looks like this
85 - ground
86 - switched power - on with key on
87 - not used
87a - ground
30 - to ground side of buzzer

 

I really appreciate this. Can't wait to try it out...

 

When I tried to hook this up I realized I did not know where to wire in the power to the buzzer. Where is it powered from? Would it be 86?

 

86 goes to something thats on when the key is on (check at the fusebox for something suitable).
the positive side of your buzzer goes to the marker light circuit, so its gets power whenever the headlight switch is on - both when its fully on or only on parking lights.

 

Josh,

Thanks again for your help. I got the buzzer wired up today and it works fine. To summarize the connections for any future electrical morons like me wishing to install a simple 2 wire headlight warning buzzer, here they are:

For a 5 pin relay (the numbers are marked on the relay). I used a Bosch.

86 - 12V from any source hot only when the key is on
87 - Not used for this application (leave open)
87A - Battery Ground
85 - Battery Ground (connections from 85 and 87A can be wired together
before connection to ground)
30 - Ground side of the buzzer

I used a common buzzer with only two wires. The red wire goes to the headlight switch. You can use the dash light connection or headlight. I used the dash light connection. The parking light connection could be used unless you have an older car/truck where the parking lights do not come on with the headlights (prior to about 1963). The black wire (ground) on the buzzer goes to pin 30 on the relay as shown above.

THAT'S ALL FOLKS!