sixwheeledbeast Posted April 22, 2019 Share Posted April 22, 2019 I was just going to say Greggs have there own facility company do it. Quote Link to comment Share on other sites More sharing options...
Gabs Posted April 22, 2019 Author Share Posted April 22, 2019 Quote Link to comment Share on other sites More sharing options...
MrHappy Posted April 22, 2019 Share Posted April 22, 2019 (edited) ↑ they have to fit widescreen cctv to fit the punters on the screen Edited April 22, 2019 by MrHappy Quote Mr Veritas God Link to comment Share on other sites More sharing options...
Gabs Posted April 22, 2019 Author Share Posted April 22, 2019 50 minutes ago, MrHappy said: ↑ they have to fit widescreen cctv to fit the punters on the screen Haha, catch them stealing the cream doughnuts! I may have a go at vacuum forming my own bell box cover, to fit around a CQR MultiBox. Is the MultiBox any good? Anybody use them? If they are ****, ill just design my own circuitry :-) Quote Link to comment Share on other sites More sharing options...
james.wilson Posted April 22, 2019 Share Posted April 22, 2019 I rate the multi box sia uses them but only the g3 one Quote securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
Gabs Posted April 22, 2019 Author Share Posted April 22, 2019 34 minutes ago, james.wilson said: I rate the multi box sia uses them but only the g3 one Okay, I have seen the ones with two piezo sounders in them. Do you have any idea how they are driven? Had an old Ventcroft Classic PCB from 1996 connected to my oscilloscope, and it is reading a very high voltage, I am assuming that it is done from the transformer on the board? Interesting waveform, it was moving in a very ordered pattern Quote Link to comment Share on other sites More sharing options...
al-yeti Posted April 22, 2019 Share Posted April 22, 2019 15 minutes ago, Gabs said: Okay, I have seen the ones with two piezo sounders in them. Do you have any idea how they are driven? Had an old Ventcroft Classic PCB from 1996 connected to my oscilloscope, and it is reading a very high voltage, I am assuming that it is done from the transformer on the board? Interesting waveform, it was moving in a very ordered pattern I think we need to clone you Quote Link to comment Share on other sites More sharing options...
GalaxyGuy Posted April 22, 2019 Share Posted April 22, 2019 Typical driver for a piezo. You'll find many examples on-line. The waveform is probably a warble or the like. I'd suggest getting a copy of Horowitz & Hill 'the art of electronics' it's an excellent reference. 1 Quote Link to comment Share on other sites More sharing options...
james.wilson Posted April 22, 2019 Share Posted April 22, 2019 Piezo needs high voltage old school mylar cone speakers need less but require more power. I prefered the lower freq as it gives more range but looks worse on spec sheets at 1m Quote securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
Gabs Posted April 22, 2019 Author Share Posted April 22, 2019 11 minutes ago, james.wilson said: Piezo needs high voltage old school mylar cone speakers need less but require more power. I prefered the lower freq as it gives more range but looks worse on spec sheets at 1m By lower spec do you mean quieter? I would love to get my hands on one of the Lynteck sirens typically found in the bell boxes of the late 80s, or early 90s. Everyone had them. They are 118 dB, and make a distinct sound, any idea how they work? https://www.lynteck.co.uk/products/intruder/sounders/LY02-009-17.php these, I bet they have some sort of custom IC. 16 minutes ago, GalaxyGuy said: Typical driver for a piezo. You'll find many examples on-line. The waveform is probably a warble or the like. I'd suggest getting a copy of Horowitz & Hill 'the art of electronics' it's an excellent reference. I will have a look online, I have seen a few, but I'm not sure if they are meant to drive something as loud as what I am after, although all I may need to do is ramp up the voltage to get the volume to increase Quote Link to comment Share on other sites More sharing options...
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