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Electronics => Electronics => Topic started by: dsesmg on August 28, 2009, 08:37:22 PM

Title: Emitter & Photo transistor
Post by: dsesmg on August 28, 2009, 08:37:22 PM
Hi, I am trying to test this photo transistor with an emitter.
The specification of the photo transistor is this.
http://www.flickr.com/photos/34955071@N02/3848158536/sizes/o/
http://www.flickr.com/photos/34955071@N02/3847368037/sizes/o/
http://www.flickr.com/photos/34955071@N02/3847368107/sizes/o/

And, the specification of the emitteris this.
http://www.flickr.com/photos/34955071@N02/3855946584/sizes/o/
http://www.flickr.com/photos/34955071@N02/3855946586/sizes/o/
http://www.flickr.com/photos/34955071@N02/3855946588/sizes/o/

I successfully got the emitter glowing. I've looked through a digital camera and I've checked a beautiful light was glowing.
The schematic for the emitter is this.
http://www.flickr.com/photos/34955071@N02/3845028272/sizes/l/
Please ignore the 1N4004 in the circuit as I've taken it out from there.

I also, got the photo transistor working. I connected a DC geared motor in the circuit and I beamed a light. The motor spins well whether I beam a light.
The shematic for the photo transistor is this.
http://www.flickr.com/photos/34955071@N02/3843611141/sizes/l/

The problem is, the transistor is not responding to the emitter at the moment.
Not at all.  :'(
Could you advise me what have I done wrong?
As you see, the operating voltage of the emitter is 1.5VDC, 60mA. So I supplied 1.5V using a variable DC adaptor(1.5~13V, 600mA). I tried to put a normal LED in the place where the emitter was.
LED is not blinking.
Title: Re: Emitter & Photo transistor
Post by: Soeren on August 29, 2009, 01:41:09 AM
Hi,

The specification of [...]
Please post a link to the datasheets (instead of pictures of the pages) next time.


The problem is, the transistor is not responding to the emitter at the moment.
Not at all.  :'(
Could you advise me what have I done wrong?
The circuit ;)


As you see, the operating voltage of the emitter is 1.5VDC, 60mA. So I supplied 1.5V using a variable DC adaptor(1.5~13V, 600mA).
No. LED's are current controlled devices and the voltage drop is not what you aim for and neither is 60mA, when your datasheet says 40mA.

This circuit should help.
(http://That.Homepage.dk/Img/IR_TX_RX.png)
The LEDs have a current limiter (Q1/R2) to keep them happy on a range of voltages and the detector is used in a voltage divider which will keep that one smiling.
The TIP102 is not a good choice for the LED driver, since it hasn't got much gain on low currents.
I don't know how much current your motor takes, but the BC337 is good for a bit more than 0.5A
If it doesn't work right away, R3 and R4 should be changed a bit, but try it in 100% darkness if it seems to keep running before you make any changes.
Title: Re: Emitter & Photo transistor
Post by: dsesmg on August 29, 2009, 05:45:15 AM
Hi, thank you very much for showing me those great schematics.
Some componentes shown in that schematics are not available now.
So, I will get them at once and test it right away.
Thank you. Have a good day.

Quote
I don't know how much current your motor takes,
It takes max 1A at 5v when it starts, and takes 0.4A at 5v in normal rotation.
That's what the supplier says.
Title: Re: Emitter & Photo transistor
Post by: Joker94 on August 29, 2009, 05:51:32 AM
Some componentes shown in that schematics are not available now.
So, I will get them at once and test it right away.

What do you mean by some components shown in the shematics are not available  so i will get them at once. ???
Title: Re: Emitter & Photo transistor
Post by: dsesmg on August 29, 2009, 06:56:22 AM
Hi, I don't have BC547, BC337, BC557 right now.
So, I am going to order for those things. :)
Title: Re: Emitter & Photo transistor
Post by: Joker94 on August 29, 2009, 07:01:14 AM
ah, that is what you ment
Title: Re: Emitter & Photo transistor
Post by: dsesmg on August 29, 2009, 08:18:50 AM
Hi, Soeren. I have a question.
Quote
This circuit should help.
(http://That.Homepage.dk/Img/IR_TX_RX.png)
Is it ok if I put 10 emitters in this circuit?
The transistor I mentioned earlier will move above the emitter and I will arrange the number of the emitter so that the transistor(motor) could stay turned on as long as it passes over the emitters.
I think I must test first, but I assume the number of the emitters needs to be 10pcs(or a little more).
Title: Re: Emitter & Photo transistor
Post by: Soeren on August 30, 2009, 02:10:44 PM
Hi,

Is it ok if I put 10 emitters in this circuit?
Sure, as long as you raise the supply voltage accordingly.
They have to connect in series of course.


The transistor I mentioned earlier will move above the emitter and I will arrange the number of the emitter so that the transistor(motor) could stay turned on as long as it passes over the emitters.
I think I must test first, but I assume the number of the emitters needs to be 10pcs(or a little more).
Didn't you see the post about the flip-flop?
Title: Re: Emitter & Photo transistor
Post by: dsesmg on August 30, 2009, 08:04:48 PM
oh. I am sorry . I missed the last post in that topic.