Topic: will this work?/alarm circuit REVISITED/UPDATED/apologies

[DH]

The schematic for a Vetter brand cycle alarm. The alarm/buzzer is
laughably ineffective at its best. Based on the schematic, would it
be possible to eliminate the supplied buzzer/alarm and substitute
a relay in its place? And in turn, use that relay to activate the bikes
own horn in the event the system was activated?

[Mr. Mike]

D,
I don't see why not. Just don't make all connections permanent till you know. Where would you locate the relay, headlight bucket?

[dave500]

it should trigger a relay ok,then hook anything to it,maybe even the headlight or flashers with the horns?

[DH]

D,
I don't see why not. Just don't make all connections permanent till you know. Where would you locate the relay, headlight bucket?

I thought about attaching the relay to the backbone of the frame under the tank, where the original buzzer used to be mounted. I'm also wondering what size/rate
relay to use that is compatible with the alarm module and will satisfy the current requirements for the stock horn. Suggestions?.........Thanks for the reply..

[DH]

it should trigger a relay ok,then hook anything to it,maybe even the headlight or flashers with the horns?

Thats an idea Dave, thanks!

[dave500]

use a common 30 amp relay?

[DH]

use a common 30 amp relay?

Thats what I'm thinkin.

[tomkimberly]

FWIW, a cell phone chip, one that would call only one number, yours, would be so cool.

No Lo-Jack needed.

Anyone how to do this?

Tom

[dave500]

how about a horrific electric shock and put it down to a dodgy dyna ignition?

[Medyo Bastos]

what is the relay going to do? that module already has a relay in it.  i would try substituting your siren first.  you may need a horn driver if the circuit cant drive the siren you choose.

[DH]

what is the relay going to do? that module already has a relay in it.  i would try substituting your siren first.  you may need a horn driver if the circuit cant drive the siren you choose.

Reason for relay is because I'm not sure the module alone would be enough to operate the bikes horn, which is my "siren" of choice. The relay would apply full battery voltage to the horn, and the module would activate the relay.

[DH]

FWIW, a cell phone chip, one that would call only one number, yours, would be so cool.

No Lo-Jack needed.

Anyone how to do this?

Tom



Also an excellent idea. Wish I knew how to do it...wayyy over my head.

[DH]

how about a horrific electric shock and put it down to a dodgy dyna ignition?

And I thought I was dangerous

[Medyo Bastos]

what is the relay going to do? that module already has a relay in it.  i would try substituting your siren first.  you may need a horn driver if the circuit cant drive the siren you choose.

Reason for relay is because I'm not sure the module alone would be enough to operate the bikes horn, which is my "siren" of choice. The relay would apply full battery voltage to the horn, and the module would activate the relay.

if you don't have full battery voltage to begin with, will the added relay boost your voltage?  i am not trying to dissuade you in any way, just feel you are giving yourself one more point of failure.

[dave500]

if the inbuilt relay is rated too low itll fail,check the resistance through the siren compared to the bikes horn.

[DH]

what is the relay going to do? that module already has a relay in it.  i would try substituting your siren first.  you may need a horn driver if the circuit cant drive the siren you choose.

Reason for relay is because I'm not sure the module alone would be enough to operate the bikes horn, which is my "siren" of choice. The relay would apply full battery voltage to the horn, and the module would activate the relay.

if you don't have full battery voltage to begin with, will the added relay boost your voltage?  i am not trying to dissuade you in any way, just feel you are giving yourself one more point of failure.

I'm not sure how much current will be available coming out of the module by itself.
The wimpy buzzer that comes with the system operates as intended, but I'm guessing, (using the bikes horn), instead of the buzzer, will require more current.
Seems like a dedicated relay would guarantee the current necessary to operate
the bike's horn, limiting the module of only having to turn another relay off/on. I.E. I think it's
easier for the module to operate an auxilliary relay than it is to power a stock horn. Please someone prove me wrong. 


PS..............Thanks again Dave. I'll keep that in mind.

[TwoTired]

Without taking the unit apart to examine the output driver section, the only method of insuring survival of the alarm unit is to measure the voltage level output and current draw of the existing buzzer, and use that measurement as a guide to what the unit will safely drive.  Do you know the buzzer is 12V? or that it is being driven with a full 12V?  An external relay would certainly shift the horn driving loads away from the alarm unit.  But, you must still insure that the current requirements for the relay activation section is still within the output capability of the alarm unit.

Buzzers can take a pretty low power input to activate.  I once worked on a  terminal using a 12v buzzer driven with 5V, It was still too loud for the office environment and we had to put a cover over it to muffle the sound.   
"Relays" cover a range of units from solid state devices to electromagnetic types.  The input current and voltage requirements can vary widely depending on selection.

You should also consider the horn amperage draw, which can also be measured.  But, if select have a 30A relay with low amperage activation input, you can probably avoid such scrutiny.

If you have a relay on hand, you can apply whatever voltage the alarm output provides from a separate device, and measure its current draw.


When the numbers all line up and coincide, wire the circuit and test in operation.

[DH]

Thanks for the reply T.T., I appreciate the information. Before I go any farther, I'll need to do some research. I'm also trying to figure out how to isolate this alarm system (how to finally wire the relay) so
the regular horn circuit and the alarm circuit work independently.
Thanks to all for the suggestions.

[Mr. Mike]

I'm no wizard, but wouldn't or couldn't you use the normally closed contacts of an 12volt 2 pole double throw relay for normal horn operation, and the normally open contacts to make  (and the n.c. to open) when the relay picks or energizes for the theft deterrent horn? Deactivation of the module would then reset the relay to it's dropped or non-energized state (horn back to normal). This application seems to make sense to me.

[DH]

I'm sort of understanding you, Mr. Mike. Will what you are suggesting
allow the alarm system to bypass the horn button? That's one of the things that's stumping me. I'm thinking I had the wrong type (style) relay in mind when I first had this brain fart of an idea I'm assuming the buzzer is 12V. and hopefully that'll be what's coming out of the module. From there, I was gonna wire in the relay's coil
in series, same way as the buzzer is,(and of course, eliminate the buzzer.) Also thinking I'll probly need to measure horn current requirements, so as to get a big enough relay. Am I makin any sense?
I grope my way thru electrics....

[Mr. Mike]

If I'm thinking right, the original horn wire (12v side), will pass through the normally closed relay contacts then proceed back to the horn terminal. You are simply passing the original wire through this closed contact. Another wire from your 12 volt "hot" supply would connect at one side of the normally open contact, and the other side of the relay contact would then go to the horn terminal connection point (2 wires now at this connection). The closing of the deterrent/alarm contact is the "button" if you will. It directly connects to the horn when the relay picks. Measure the output to the buzzer unless it's not noted in the instructions somewhere or on the buzzer itself. I don't think you need a "big" relay, just one with a contact rating that matches your horn current draw. A small "ice cube" type relay should suffice and can be found at Radio Shack, or any electronics outlet. I would suspect 30 amps way too large. Place an inline fuse in the horn circuit and start with 5 amps or even smaller and see if it holds for a minute or two with your horn blaring. If it does...just leave it in. Just a thought here; Might you consider a separate horn mounted under the seat pan or some other location where the wires can't just simply be cut or yanked off?

[DH]

The switching modes look right to me, but what GROUNDS the horn itself when the alarm is activated? Or am I missing something?
 Do I need to wire in another relay (N/O) on the negative side of the horn circuit, that would activate and provide a path to ground for the horn? (ONLY when in alarm mode.) Thus, bypassing the horn button.

P.S.    Reason I don't add another horn elsewhere is because this system fits invisibly pretty much. Also, I just like the idea, kind of "integrating it if possible. I aint even sure yet if the module for the system is up to the task to make it work......

[Mr. Mike]

D,
Take a look at the electrical diagram on this site. It looks as though the horn has a 12 volt potential at one side (black wire, IG>ON) and the circuit is grounded (light green I think it said) to honk it. In this case, forget switching 12 volts as mentioned earlier to activate the alarm as the module should provide this voltage with the ignition off. With 12 volts present from either source (IG> OFF= module is hot 12V source ), the horns gotta be grounded to honk. This is how it looks to me. When the relay picks, it has to ground the horn through the normally open contacts which should be just like holding the horn button in constantly. Remember...I am no wizard. HA! Sorry to mess you up. Now I just wanna see if this thing works for you!

[wowbagger]

In my experience, lights and car siren alarms are largely ignored by most people. IMHO, you'd be better off wiring in a gps tracker.

[DH]

It's been a while since this was posted, so apologies for taking so long. To review, in a nutshell, my idea was to use an aftermarket alarm module to activate my bikes stock horn, instead of using the wimpy buzzer that came with the alarm kit. I'll post the diagram, and hope you all will bear with me as I grope thru this bright idea.
The diagram below shows the use of two (2) SPDT relays. (Green arrows) point to relays, (RED arrows) point to triggers. The triggers are arranged in series, and TAKE THE PLACE of the alarm buzzer in that circuit. If the alarm is ever activated, the TRIGGERS of the relays
switch on and off, as commanded by the module. The load carrying portion of both relays are arranged in such a manner that power and ground are supplied to the bikes horn (on-off beep) even when the ignition is turned off and key is removed.
I think what I have will work.....kinda..
The only thing I haven't yet figured out is current draw rating of the old buzzer
that I removed. Does the old buzzer need to be hooked up and functioning as
a working component? And, from there, do amp drop test? Or, can I get by with substituting an ammeter, IN PLACE OF the buzzer, in series, activating the alarm and and read currentflow thru the meter?..I will stop here and wait.opinions/theories?........Thanks for your thoughts, and I'll stay with it this time.