Laser Burglar Alarm -- Need Help

[john1]

if its legs are long enough,
just touch it on

 

[john1]

it might sound the same on the siren,
but check with the meter,
if its alright there

 

[Anonymous321]

Well the meter reading for the 47k seemed the same as the 33k. But as for the sound difference, the 33k gave more sound. This is opposite to what you just said....I'll try again.

 

[john1]

must have just arrived at pretty much the right value,
if a higher value makes a difference.

So next is the sensor.

 

[Anonymous321]

Ok, should I put the photocell on no4 and no5? One wire going from no1 to no4? And then another wire going from no5 to no21 (which is -ve of 9V)?

 

[john1]

The sensor would go between 1 and 3 terminals.

Have a torch or laser light ready, to quieten it,
or be ready to flick off the battery connector.

And i would like to see that sensor a bit better,
it might be polarity concious.

Any markings on it?
Or is one leg distinctly longer than the other,
thats another way they show polarity sometimes.

 

[Anonymous321]

Ok, I'm taking more pictures of it. I don't think one leg is longer than the other.

So you want me to put the photocell on the base and the emitter then?

Well I'm going to do that after I post some pics of it for you.

This is the link for it:
**broken link removed**

 

[john1]

Okay,
then you're pretty much done.

The resistor that you settled on should be high,
but not so high as to start affecting the output.

that has to go on too.

Once its all together,
it will only be quiet if light shines on the sensor.

So have a torch ready, or be ready to flick off the battery.

 

[john1]

I had a bit of a look at that sensor on an earlier pic,
i couldn't see any polarity to it.

See what you think.
I dont think it would harm it, if it was polarised,
and got connected backwards, as its only on the base-emitter junction.

But it doesnt look polarised.

 

[Anonymous321]

Well I can't get any good pics of the photocell. I hope you were able to see it. Here is what the top basically looks like:
https://www.futurlec.com/Pictures/Photocell.jpg

So now I have to:
- photocell on no1 and no3. It doesn't matter which lead on what terminal right? B/c I can't seem to tell a difference in the lengths.
- resistor ATTACH on to no1 and no6?

 

[john1]

Make sure you've got a spare battery when you come to show it.
You dont want to be let down by something silly.

John

 

[john1]

Yes attach the resistor to make it go.
Shine the light to make it stop.

 

[john1]

I hope it works alright,
we havent had it stop yet from the laser ...

 

[john1]

Daylight is creeping up here ...
i must go soon

 

[Anonymous321]

I think this laser is weak (it's "shine" is dimmer than before). I'm going to try another one. I chose the 47k resistor by the way. The laser was able to muffle the sound only slightly. I'll try it fast.

 

[Anonymous321]

It works with my doesn't-get-dim-2-days-after-I-buy-it laser!

 

[Anonymous321]

You're awesome, John! I love you (in a respectable way)!

 

[Anonymous321]

Yeah, I'm definitely going to be bringing spare parts on presentation day. For now, I'll draw the schematic, analyze how everything is working, and confirm with you tomorrow (if you'd like).

 

[Anonymous321]

Thanks a bunch! And I'm deeply sorry for keeping you up so so late. Hopefully, in the future, I'll be able to help you. Haha fat chance but I'll try.

 

[Torben]

Good job Anon and John! I had to run out to my wife's softball game. Looking forward to seeing the schematic and hearing how the presentation goes.


Torben