16 minutes ago, MrHappy said:

Revann Electronics ?

Yes, I think so. Why?

Just now, Gabs said:

Yes, I think so. Why?

He's just a alarm enthusiast got nothing better to do

1 hour ago, Nova-Security said:

My typo meant 4047 

Could do it with a 555 if you could get the mark/space ratio equal, one LED to + rail the other to -

Yes, a 4047. I find a 555 much more flexible in a smaller package.

You are right tho it's the right chip for a 50% duty cycle multivibrator.

 

57 minutes ago, Gabs said:

I was thinking of using a betray like this: https://uk.rs-online.com/web/p/coin-button-rechargeable-batteries/0525815/ bit safer than a Lithium one.

I was thinking of a 7.2V NiCd/NiMH like most alarm bells do. While it is listed as Li-ion charger circuit it would be suitable for other cells. Actually, I would say it's more suited to Ni cells.

4 minutes ago, sixwheeledbeast said:

Yes, a 4047. I find a 555 much more flexible in a smaller package.

You are right tho it's the right chip for a 50% duty cycle multivibrator.

 

I was thinking of a 7.2V NiCd/NiMH like most alarm bells do. While it is listed as Li-ion charger circuit it would be suitable for other cells. Actually, I would say it's more suited to Ni cells.

I will take that into consideration, those cells are much safer than lithium ones, but I'm surprised at how little there is in the way of circuitry on the board of the SAB I have, is the battery constantly charged until needed? I have ordered the relay I will be using for my circuit 

8 minutes ago, Gabs said:

I'm surprised at how little there is in the way of circuitry on the board of the SAB I have

 

Possibly an SCB, from looking at the traces in the photos.

Battery negative runs into the contact of the relay?

Says Leyland on the buses but they don't all go there...

6 minutes ago, sixwheeledbeast said:

 

Possibly an SCB, from looking at the traces in the photos.

Battery negative runs into the contact of the relay?

Says Leyland on the buses but they don't all go there...

Yeah, that is correct, the negative of the battery goes into the relay. It would be very easy to make a bell module with no charging circuit, you'd only need a relay. Board looks hand-etched too. And it could be SCB, it is powering a bell, not an electronic siren, so I can't imagine that battery lasting long anyway. It amazingly still holds a charge. 

 

Think I have cracked the part without the battery charging circuit, really quite simple 

Would normally be a single -ve applied for the trig.

1 hour ago, Gabs said:

Yes, I think so. Why?

 

never seen anything or heard of this co. before, however

 

 01297445    REVDUN ELECTRONICS LIMITED          Dissolved 22/05/1993
 01907384    REVDUN SECURITY PRODUCTS LTD.    Dissolved 06/11/1990

 

Google throws up your topic on here about a panel & a linkdin page which say they where in Birmingham ?

 

 

2 hours ago, MrHappy said:

 

never seen anything or heard of this co. before, however

 

 01297445    REVDUN ELECTRONICS LIMITED          Dissolved 22/05/1993
 01907384    REVDUN SECURITY PRODUCTS LTD.    Dissolved 06/11/1990

 

Google throws up your topic on here about a panel & a linkdin page which say they where in Birmingham ?

 

 

Stalker