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photo-interrupter circuit

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KSP 2222A -J12 TO-92 package

According the data for the 2222 and the TIP there shouldnt be a problem.
Are you sure that 'load' in not more that 1Amp.

Try connecting another 100R in parallel with the existing 100R, increase the base drive to the TIP.
 
hi,
A more efficient method would be to use a P Channel MOSFET, say a FDS6875, [in place of the TIP] this would reduce the voltage drop thats appearing across the TIP.

If you decide to use a MOSFET, I'll redo the circuit.
 
5v 750ma lamp amps increase from 31ma to 42ma and voltage from .77 to 1.78 when 2 x 100R in parrallel (ie 50R)
 
5v 750ma lamp amps increase from 31ma to 42ma and voltage from .77 to 1.78 when 2 x 100R in parrallel (ie 50R)

hi,
That should not be happening, there is another problem on your circuit.
Check that the TIP32 is the correct way around.

For ref this image is using a MOSFET, its more efficient thatn the TIP.
 

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Thank you very much for your help Eric

Whilst experimenting I figure that rather than a "hot" tip32 I will run a relay.

You helped me invert the signal to make the output switch off rather than on as in the original circuit.

As the device would have been on most of the time I didn't want to have a relay always energised but now it will only be energised for the shorter period.

Finding a suitable amperage relay was nigh impossible however this one **broken link removed** functions perfectly @ 45ma.

Changing to a reflective photo interrupter has meant a 50ma led circuit and a variable resistor on the emitter of <2k.

Sorry to be such a pain but You don't know how much I appreciate your assistance.

I too once was giving others assistance like you but no longer.

**broken link removed**

Again thanks Guru
 
hi,
Have a look at this option.

Using the above thumbnail circuit included in the post above (but with a common rail @ 5v and a single pole double throw relay instead of tip32) combined with the following circuit

I am going to switch this bi-polar stepper motor circuit

Silicon Chip Online - Circuit Notebook

The stepper motor is 5 volt so will power all at 5 volt.

I want to switch off the motor by the opto interrupter and restart it by a momentary switch

I find that leaving the motor energised causes overheating whilst stationary (ie removing step/oscillator link)

Given that I are only able to access a single pole relay of suitable rating (1amp), where in circuit would it be best to switch off the motor supply and where would it be best to restart the circuit by using a 50ma switch
0.7MM SPST MICRO TACTILE SWITCH
- Rating: 12VDC 50mA
(**broken link removed**)

Thanking you in anticipation
 
hi,
Is this the circuit you plan to use, if yes, then the FET's will not switch ON fully with a 5V gate drive.????
 

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Meaning?

That the Mosfets get hot if not switched fully on?

What about where to switch off and where to switch on
 
Meaning?

That the Mosfets get hot if not switched fully on?

What about where to switch off and where to switch on

Look at these two plots, the circuit and MOSFET's are designed to work a 12V supply.
 

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hi,
Is this the circuit you plan to use, if yes, then the FET's will not switch ON fully with a 5V gate drive.????

1/ So page 6 of https://www.electro-tech-online.com/custompdfs/2009/04/K179notes.pdf showing a 8-35vdc @ CN3 (connector 3) and page 6 of **broken link removed** showing 5-50vdc are wrong using less than 12vdc at Mosfet Gate?

2/. Can I replace the mosfets with a transistor and diode? (Motor is 2.75-7.2vdc, 12 ohm, Current is .44 amp @ 3v .8 amp @ 5v, 1amp @ 6v)

3/. Where would be the best location to restart the motor after the photo interrupter has deactivated the relay bearing in mind using a 50ma tactile switch
a/. Across the photo interrupter output emitter collector, b/. across transistor BC337 c/. across the transistor 2N2222 d/. or where else and how

Thanking you
 
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1/ So page 6 of https://www.electro-tech-online.com/custompdfs/2009/04/K179notes-1.pdf showing a 8-35vdc @ CN3 (connector 3) and page 6 of **broken link removed** showing 5-50vdc are wrong using less than 12vdc at Mosfet Gate?

2/. Can I replace the mosfets with a transistor and diode? (Motor is 2.75-7.2vdc, 12 ohm, Current is .44 amp @ 3v .8 amp @ 5v, 1amp @ 6v)

3/. Where would be the best location to restart the motor after the photo interrupter has deactivated the relay bearing in mind using a 50ma tactile switch
a/. Across the photo interrupter output emitter collector, b/. across transistor BC337 c/. across the transistor 2N2222 d/. or where else and how

Thanking you

hi,
Ref the single pole relay, looking at the circuit there is no point in the circuit where a single pole 1amp contact relay could be used to switch off BOTH HBbriges.

The other point that you should consider, is if you switch off the +5V, the powered 'holding' torque of the motor will be lost and the 'load' that the motor shaft is driving could move from the set position.

There are P/N MOSFETs that will operate on a Vgs of about 2.5V, replacing the MOSFETs with transistors would mean a major change to the circuit.

On the web there are transistor HBridges also HBridge ic's.
 
1/.Would switching off the 12v+ supply to source of h bridge mosfets stop the mosfets or motor getting warm?
(The motor requires no holding torque.)

2/. Where would be the best location to restart the motor after the photo interrupter has deactivated the relay bearing in mind using a 50ma tactile switch
a/. Across the photo interrupter output emitter collector, b/. across transistor BC337 c/. across the transistor 2N2222 d/. or where else and how
 
1/.Would switching off the 12v+ supply to source of h bridge mosfets stop the mosfets or motor getting warm?
(The motor requires no holding torque.)
It should do, if the full bridge is switched.

2/. Where would be the best location to restart the motor after the photo interrupter has deactivated the relay bearing in mind using a 50ma tactile switch
a/. Across the photo interrupter output emitter collector, b/. across transistor BC337 c/. across the transistor 2N2222 d/. or where else and how

Add a 2.7K resistor to the base of the relay drive transistor and use the tactile switch to connect the 2.7K to the 5V or 12V rail.
 
A tactile switch across the emitter collector would be ideal.

Is this possible and is a 2k7 resistor suitable
 
A tactile switch across the photo interrupter emitter collector would be ideal.

Is this possible and is a 2k7 resistor suitable
 
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