GCSE Alarm

[bigevil-wba]

Hi, i'm currently starting my alarm c/w and I was wondering, as I'm using pressure pads, would be OK with using a latching thyristor as I would also likemy alarm to oscillate.

 

[Spark123]

Don't quite get what you mean by a latching thyristor, could you use logic (74ls) series semiconductors? Relays? For oscilations I always found the 555timer circuit one of the easiest ones to make.

 

[andy]

Hi, i'm currently starting my alarm c/w and I was wondering, as I'm using pressure pads, would be OK with using a latching thyristor as I would also likemy alarm to oscillate.

AFAIK, all thyristors latch, and the input has to be interupted to 'reset' it. transistors dont normally latch

 

[andy]

Don't quite get what you mean by a latching thristor, could you use logic (74ls) series semiconductors? Relays? For oscilations I always found the 555timer circuit one of the easiest ones to make.

depending on voltage, it might be better to use CMOS 4000 series instead of TTL. i would imagine the alarm would use a 9V battery and TTL needs 5V

 

[Spark123]

Voltage regulators?

AFAIK, all thyristors latch, and the input has to be interupted to 'reset' it. transistors dont normally latch

Yup, your right, see http://en.wikipedia.org/wiki/Thyristor

 

[Adam_151]

Voltage regulators?

Yup, specifically, the 7805 in the context of this

 

[TexMex]

If you use a 555 you don't need a seperate latch. This circuit would do the trick, and latch itself. Obviously this is actually a tilt switch for a pinball machine, but the principle is the same. Simply remove the mercury switch and replace it with your pressure mat.

 

[andy]

Voltage regulators?

was tryin to keep it simple. altho if he did want to make it harder, then 7805 would do, and a few caps

 

[ebee]

Hi, i'm currently starting my alarm c/w and I was wondering, as I'm using pressure pads, would be OK with using a latching thyristor as I would also likemy alarm to oscillate.

A relay is a good latch and pretty immune to other votltages,
Back to basics as Mr Major Said.

Q Why do people try to get rid of Acne with sandpaper?

Stark raving Mad they are why do they do it?

 

[slippyr4]

insert obligatory part p joke here/

 

[ban-all-sheds]

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