alarm piezo voltage

[keendiyer25]

hi there, i have been servicing my elmdene internal sounder and got a pretty painful shock from the white piezo wire at the transformer whilst testing the sounder using those stupid neon screwdrivers which turned out to be faulty so i binned it, i was quite shaken afterwards but it was my own fault lol.

my question is what voltages do these piezos run at when sounding?, the shock was almost as bad as a normal mains 240 volt shock which is painful, god knows what would of happened if it was the strobe i would have probably been electrocuted i heard they go up to 300v sometimes higher

 

[keendiyer25]

it seems that burglar alarms can be just as dangerous as mains electric, well the sounder and panel maybe dont know about detectors and other devices on the alarm as their 12v maybe they could be dangerous if you touch the wrong part like i found out the hard way lol

any thoughts

 

[EightyTwo]

It will have been the strobe, not the piezo sounders and, yes, it's a few hundred volts, with a few thousand volts to strike the arc!

Never mess with the inside of a bell when the strobe is in use. Leave it for at least five minutes after the last flash.

 

[Europlex]

Not trying to be rude but what are you doing 'servicing' something you so obviously know nothing about.
Just imagine what would have happened if you had been up a ladder when that happened.

Strobes hurt if not handled with respect.

 

[keendiyer25]

hi 82 and europlex i do have some knoledge about alarms [ie wiring sensors to alarm panel and changing batteries] but i will admit i know pretty little about the sounder circuitry, having realised they use step up tranformers and high voltage capacitors to energisze strobe and sounder. 12v volts charges the battery and comfort leds but clearly not the strobe lol.

also there is a transformer for the piezos what voltage do they run when sounding

ps i was changing the backup battery and when it went off i jumped and accidently hit the transformer and got jolted

 

[keendiyer25]

so what voltage do these piezos run at when sounding 100v,200v or less? id just like to know what im up against cheers,

straight answer please

 

[bernardgreen]

Many small piezo elements operate on 5 volts and most are listed as maximumn of 25 volts on their data sheets

Some driver circuits have an inductor which creates a reverse polarity pulse to the element to create a pseudo AC waveform. ( driving a piezo with DC can reduce its life ).

I doubt this pulse would be large enough to cause a shock.