How do i use these thingys?

[Deleted member 42405]

http://m.ebay.co.uk/itm/4PCS-or-1-x...7-/291206924133?nav=SEARCH&varId=590361475946

Can I just wire one of these to a circuit and have them close the circuit when it senses ir light?

 

[Martaine2005]

Hello LOSER!,
Generally you would need a circuit that employs other switching too.
The phototransistor is just like/similar to a regular transistor, except the base is the IR light.
You can use them to 'turn on' a transistor and that will open or close a circuit.

Martin

 

[Deleted member 42405]

Didnt realy get that... Do I need a regular transistor to use them or something?

 

[Minder]

If you are technically challenged You could input it into a SSR Solid State Relay if you wish to switch a AC load, see ebay 201414937205
M.

 

[Martaine2005]

Didnt realy get that... Do I need a regular transistor to use them or something?

Normally yes. But by all means not always.
It would obviously depend on what you are controlling and the circuits voltages and current.
But yes, it is just a switch!

Martin

 

[Deleted member 42405]

Theres a circuit that i found that uses it as if its a switch, exept they use clear ones. Do the black work the same as clear or ate they differences?

 

[Martaine2005]

They are different.
IR leds are not IR phototransistors.
Both are diode classes. As are all leds and transistors. I have heard of normal blue leds being used too.
But that is far beyond my experience.
If you have seen the circuit, try it!

Martin

 

[Minder]

What are you trying to control?
M.

 

[Deleted member 42405]

Im trying to make a very simple circuit for losers like me. All its supposed to do is turn on an led when it detects ir light. The only thing is, the ir transistor in ths circuit is clear but these are black so am wondering if it would do the same thing. Their both transistors not leds. Also, the battery used is a 9v one, but is it realy necessary to do that or can i power it from, i dunno 5v? All it is is an led connected to a phototransistor and a 330ohm resistor so the led wont blow. I cant post a link coz copy and paste is failing me.

 

[Martaine2005]

Loser,
You need to read/check the datasheet for your individual leds/transistors.
They all have different operating voltages and currents.
Some might switch several Amps while others will only work on micro amps.

Post your circuit..

Martin

 

[Deleted member 42405]

Apart from the leds i havnt realy got the stuff yet. I suppose it realy depends on how much voltage the transistor needs.

http://www.instructables.com/id/9V-IR-detector/

 

[Martaine2005]

Loser,
Yes, in the circuit you show, the phototransistor is the switch to turn on the led.
Covering it will dim or turn it off..
I think some good advice would be to learn Ohms law. If you want to play with leds and batteries, ohms law really helps to stop destroying your leds..
It's not difficult......Well it is for me
But....Voltage / Current = resistance.

 

[Deleted member 42405]

So the rated voltage of the led / the current going through it? Or the voltage of the power source or... Wha?

 

[BobK]

Here is a circuit that might work:



Q1 can be any PNP switching transistor.
R2 should be as shown for a red LED, lower (maybe 68) for a white LED. This assumes 20mA LEDs.
R1 will adjust the sensitivity, try a range of 1K to 10K. If you have a 10K pot, you can use that, and adjust it.

As far as the clear vs black ones, the black ones block out visible light so they respond only to IR light. If it is your intent to detect IR light in the presence of visible light, the black ones will work better.

Bob

 

[Martaine2005]

Thanks Great Great Great Bobs your Uncle....

 

[Deleted member 42405]

Thanks I think i might make it acccording to the instructable tho- i have no idea which transistors I have have absolutely no idea how many ohms my resistors resist (the markings are a little weird) and its just too much headache getting hold of all this stuff just for a little reciever. However the pot was a great idea and i think ill add one of them in somehow. And thanks for the tip about the black vs clear thing.

 

[Minder]

Measure them, or consult the chart.
https://www.electronicspoint.com/threads/memorable-resistor-color-code.276640/
M.

 

[dorke]

Here is a circuit that might work:

View attachment 23807

Q1 can be any PNP switching transistor.
R2 should be as shown for a red LED, lower (maybe 68) for a white LED. This assumes 20mA LEDs.
R1 will adjust the sensitivity, try a range of 1K to 10K. If you have a 10K pot, you can use that, and adjust it.

As far as the clear vs black ones, the black ones block out visible light so they respond only to IR light. If it is your intent to detect IR light in the presence of visible light, the black ones will work better.

Bob

Bob,
A "typo" in your circuit,
as it is it will not work since C-E need to be switched,here:

 

[BobK]

I don't think so, is it a PNP.

I simulated it and it does work.

Bob

 

[dorke]

I don't think so, is it a PNP.

I simulated it and it does work.

Bob

Can't you see the LED current and Emitter "Current directions" are opposing ?
Furthermore, the BE of the PNP can never be foreword biased in this circuit.
It could work ("In reverse logic") if your transistor would have been NPN, but not with a PNP !