Electronics Forum

Electronics Circuits & Projects discussion forum. Get help with electronics.


Phototransistor circuit

Discuss about electronic circuits here. Request help for circuits that you couldn't find anywhere else, how a circuit works etc. Discuss anything related to electronic circuits.

Moderator: pebe

Phototransistor circuit

Postby gravymister » Fri Jul 24, 2015 2:22 pm

Hi,
So I'm trying to design a phototransistor circuit where by when an object comes near a light comes on - its going to be applied to a beer pong table.

I Designed this circuit originally:
[img]http://s29.postimg.org/9rd5mvi3r/circuit_2.png[/img]
with an R2 of around 50 ohms and R1 of around 100 ohms (I tried higher resistances which I found increased sensistivity but not brightness)

My problem was that the white LED never got bright enough even with IR led pointed directly at the phototransistor

These are the parts used:
Phototransistor: Osram Opto SFH 310 FA 50 ° Infrared Phototransistor, Through Hole 3mm Package
IR LED: Osram Opto LD 271 IR LED, 950nm, 2-pin Through Hole T-1 3/4 (5mm)

So I thought it might be wise to use a transistor to amplify the current to the white LED like such:

[img]http://s28.postimg.org/ob27o3lbh/cicuit_3.png[/img]

I tried this with a transistor I had, but the white LED remained on, assuming the circuit design is legit, I'm not sure how to decide on which transistor to use?

Any help would be greatly appreciated.
Thanks
gravymister
 
Posts: 2
Joined: Fri Jul 24, 2015 2:14 pm

Re: Phototransistor circuit

Postby KMoffett » Fri Jul 24, 2015 8:20 pm

What's your supply voltage? What transistor did you use? And which of its pins (C B E) went to the + supply?

Ken
KMoffett
 
Posts: 190
Joined: Sun Apr 13, 2014 3:41 pm
Location: Minnesota USA

Re: Phototransistor circuit

Postby gravymister » Sat Jul 25, 2015 4:39 pm

Its a 5v circuit. The collector was positive. The transistor was a c1815 (thats what it says on the back)
gravymister
 
Posts: 2
Joined: Fri Jul 24, 2015 2:14 pm

Re: Phototransistor circuit

Postby KMoffett » Mon Jul 27, 2015 2:34 am

I would move the LED/R1 to between +5V and the transistor's collector, with the transistor's emitter to common.

Ken
KMoffett
 
Posts: 190
Joined: Sun Apr 13, 2014 3:41 pm
Location: Minnesota USA


Return to Electronic Circuits Help



Who is online

Users browsing this forum: No registered users and 1 guest

Johnson Metasys M4-CGM09090-0 M4 General Purpose Application Controller OEM NOS
$199.95
Johnson Metasys M4-CGM09090-0 M4 General Purpose Application Controller OEM NOS pictureJohnson Controls Metasys DX-9100-8454 Extended Digital Controller Rev B
$35.99
Johnson Controls Metasys DX-9100-8454 Extended Digital Controller Rev B pictureJohnson Controls Metasys Controller CVM03050 Module Board
$138.75
Johnson Controls Metasys Controller CVM03050 Module Board pictureJohnson Controls M4-SNE22000-0 Metasys SNE22000 Network Engine 24V 0.4A
$1900.00
Johnson Controls M4-SNE22000-0 Metasys SNE22000 Network Engine 24V 0.4A picture


cron