self test warning buzzer

[snoman820]

I have a boat with a temperature warning horn on it. They want an arm and a leg to replace the warning horn in the unit. I would actually rather have one in the dash rather than on the controls. It is a simple circuit in the fact that it is fed power to one side and the when the temp switches close it completes the ground. I have no problems wiring that up.
The switch currently has a self test it does on itself. Whenever you turn on the key it beeps for half a second. I would like to put a beeper and light in the dash and still have this half second beep when the power is provided to it. It is currently built into a 1 inch cube box so the circuit shouldn't be too tough.
Can someone point me in the right direction how to wire something like this up? Is it a simple inexpesive thing I can get parts at radio shack or something?
Thanks for the help.

 

[ericgibbs]

hi,
Look at this link for a range of sounders.
Your Search Results | CPC

 

[snoman820]

Thanks for the link to the sounders. That part I know I can get locally as well. The main question is how to I get it to beep for about a 1/2 second when the power is first supplied to it?

 

[ericgibbs]

Thanks for the link to the sounders. That part I know I can get locally as well. The main question is how to I get it to beep for about a 1/2 second when the power is first supplied to it?

hi,
Are you able to buy basic electronic components locally.?
I could draw a simple circuit.

 

[snoman820]

I am pretty sure. We have a radio shack and they do carry quite a few drawers of misc stuff.

 

[ericgibbs]

I am pretty sure. We have a radio shack and they do carry quite a few drawers of misc stuff.

OK.
I assume as it marine system its 12V or 24v battery.?

As well as the 0.5sec Power Up beep and Light, do you want 'beep test' button.?

 

[snoman820]

It is a 12 volt system. I do not need a test button. It just beeps once when the key is turned on. Then the only way it would "alarm" is if the temp switches ground the circuit. I figured if I move it to the dash I would put a red light in the circuit as well for a visual as well as an audio. Thanks for you help.

 

[ericgibbs]

It is a 12 volt system. I do not need a test button. It just beeps once when the key is turned on. Then the only way it would "alarm" is if the temp switches ground the circuit. I figured if I move it to the dash I would put a red light in the circuit as well for a visual as well as an audio. Thanks for you help.

hi,
I have had a quick look at circuit that should do the job.
If you can get a 12Vdc, panel mounted Sounder, let me know the type [ mainly the current it draws when operating ] so that I can select the driving components.
The sounders come in different levels of sound intensity, I think around 96dB should be OK.

I would suggest a panel mounted Super Bright LED as a visual indicator, they are more reliable than a lamp and comparable brightness.

Final point, can you confirm that the temperature sensor switches to the boats 0V battery [ground].

 

[snoman820]

I will have to see what is available for sounders. I will have to run over and see what they have. I am sure I can find an led light there as well. The ground does indeed ground to the chassis/motor ground, which is right to the negative of the battery. They only ground when the motor overheats so they are normally open.

 

[snoman820]

Is it a pretty simple configuration to make it self test beep when the the key is turned on? That is the part I am in the fog on, but I figured if they fit it in a little tiny 1 inch box on the original, it can't be too complex. Its technology they used in 1994, but I think were using all the way in the early 80s.

 

[KMoffett]

I think this will meet your requirements. The horn and switch to the right of the dashed line is the original. The circuit to the left will briefly activate the SONALERT and LED when the Ignition is turned on. The SONALERT and LED will be activated continuously when the over-temp switch closes. With a small relay it should be fairly compact. R1 and C1 determine the length of the brief start-up alarm.

Ken

 

[snoman820]

Well, that has a few more componants than I thought it would, but what you have figured out is exactly what I want the system to do. The problem is I have no idea what some of those electrical symbols mean. I am hoping radio shack has that stuff. Is there a site or something I can refer to for a legend of all the symbols and such. I work in Automotive and the diagrams usually don't get that complex.

 

[KMoffett]

I think Radio Shack stuff will work. I'm on my way home so will look up some part numbers.

Ken

 

[snoman820]

Cool, that sounds great. I see there is a relay in there. I have a small 12 volt relay I could maybe use already. It's the other stuff with the diodes, resistors, and transistors I am not clear on.

 

[carbonzit]

I think this will meet your requirements. The horn and switch to the right of the dashed line is the original. The circuit to the left will briefly activate the SONALERT and LED when the Ignition is turned on. The SONALERT and LED will be activated continuously when the over-temp switch closes. With a small relay it should be fairly compact. R1 and C1 determine the length of the brief start-up alarm.

Don't want to pick too many nits here, but couldn't you get away with just an opto-isolator instead of a relay, and eliminate the FET and the catch diode altogether? (If the opto will handle the current from the horn and buzzer, that is.)

Hmm, scratch that: just did a quick check at DigiKey, and it seems nothing's available that'll do the job here. They have a few high-current optoisolators (2-5A), but they're ungodly expensive.

 

[snoman820]

I will let you guys figure this out. I am lost already. Maybe this should be a new hobby of mine so I can learn a little more.
The 1/2 second beep at key on would not have to be exactly a 1/2 second. If it were anywhere from 0-1 second I would be happy.

 

[carbonzit]

I think we got that. This is not a high-precision ciircuit.

Ken's circuit is about as simple as it's gonna get. Once you get the parts, it'll be easy to assemble. You do know how to solder, don't you? If not, it's easily learned, and this is the perfect project to learn it on.

About getting the parts, not sure Radio Snack will have all of them (I doubt they'll have that transistor and the Sonalert). Is there by any chance a real electronics store near you? If not, there's always mail order, though that's a pain if you're itching to go now.

 

[KeepItSimpleStupid]

The KRDS SSAC timing relays would be appropriate.

 

[KMoffett]

IRF510 MOSFET (instead of 2N7000)RadioShack.com
1N4001 diodes (instead of 1N4148) 1N4001 Micro 1A Diodes - RadioShack.com
1KΩ resistor 1K Ohm 1/4-Watt Carbon Film Resistor (5-Pack) - RadioShack.com
100KΩ resistor 100K Ohm 1/4-Watt Carbon Film Resistor (5-Pack) - RadioShack.com
4.7uF capacitor (instead of 47uF...too long a alarm) 4.7 uF Electrolytic Capacitor - RadioShack.com
SONALERT/Buxxer 95dB Panel Piezo Buzzer - RadioShack.com
LED (LED+1K resistor) http://www.radioshack.com/product
/index.jsp?productId=2062570
12V Relay(not small but easy to connect) http://www.radioshack.com/product
/index.jsp?productId=3020762

Radio Shack has to have the absolute worst search engine of any vendor I've ever encountered.

Is the existing "horn" working?

Ken

 

[KMoffett]

Actually, I do have a slightly more simple monostable circuit. You lose the MOSFET, a resistor ,and a diode, but the capacitor is much bigger.

Ken