IR sensor and a DC motor

Thread Starter

Jonasz

Joined Aug 26, 2016
9
Hi, I'm making a paintball pistol with a electronic loader for 50 rounds :D
It is almost complete, just need a simple circuit to finish
I never made a circuit before or studied electronic, that is why I'm seeking for help

I need a very simple circuit, Just a IR sensor that make a DC motor run when it receives IR light



That is what I tried to do:
Motor nao gira.jpg

But the motor does not run :(


With a white Led instead the DC motor the circuit works

If I curt-circuit from the collector to the base on the transistor the DC motor works


What should I do?

Sorry for my bad english, I'm from Brazil
Thanks
 

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wayneh

Joined Sep 9, 2010
16,114
With a white Led instead the DC motor the circuit works
Do you mean it works when the white LED is oriented in the opposite direction compared to the diagram, so that it conducts and lights?

What IR diode are you using? That term is usually used for something that emits IR light, not receives it. Even if it is a receiver, it probably cannot pass enough current to turn the transistor on and run the motor.

There are several solutions depending on what you have available. A darlington transistor (two transistors) to replace the 2N3904 may be the simplest, if your diode truly is a receiver.
 

Alec_t

Joined Sep 17, 2013
10,432
I need a very simple circuit, Just a IR sensor that make a DC motor run when it receives IR light
Welcome to AAC!
In a 'very simple' circuit the LED will respond to normal daylight. Is that what you want? If you instead want to send a command to operate the motor then bear in mind that IR remote controls for TVs etc use transmitter and receiver modules which work with pulsed ultrasonic-frequency (typically ~38kHz) IR signals.
Take a look at this to get an idea of what is involved.
 
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ian field

Joined Oct 27, 2012
6,540
Hi, I'm making a paintball pistol with a electronic loader for 50 rounds :D
It is almost complete, just need a simple circuit to finish
I never made a circuit before or studied electronic, that is why I'm seeking for help

I need a very simple circuit, Just a IR sensor that make a DC motor run when it receives IR light



That is what I tried to do:
View attachment 111055

But the motor does not run :(


With a white Led instead the DC motor the circuit works

If I curt-circuit from the collector to the base on the transistor the DC motor works


What should I do?

Sorry for my bad english, I'm from Brazil
Thanks
AFAIK: the TV front panel IR receiver chips also respond to steady light and produce similar to an open collector TTL output.

As long as my theory is right; it'd work very nicely with a logic level MOSFET.

You have to regulate its supply, but a 78L05 doesn't take much space - every one I've seen on a TV front panel had a local 100R resistor and a small decoupling electrolytic, its probably for all the digital hash in modern TVs, but I'd duplicate it just in case.
 

AnalogKid

Joined Aug 1, 2013
8,138
What he said is that when he replaces the motor with a white LED, the white LED comes on when the photodiode is illuminated. My guess is that there is enough base current to turn on an LED with 5 mA, but not run a motor with 200 mA. If a 3904 can handle the motor current, what about a 2N7000 instead, with a 1 M pulldown resistor on the gate?

ak
 
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Thread Starter

Jonasz

Joined Aug 26, 2016
9
Thanks for the answers

Do you mean it works when the white LED is oriented in the opposite direction compared to the diagram, so that it conducts and lights?
What IR diode are you using? That term is usually used for something that emits IR light, not receives it. Even if it is a receiver, it probably cannot pass enough current to turn the transistor on and run the motor.
I asked for the seller for a IR receiver
If I use a led instead a motor it works:
Led acende.jpg


If I curt circuit the receiver the motor run:
Motor gira.jpg



There are several solutions depending on what you have available. A darlington transistor (two transistors) to replace the 2N3904 may be the simplest, if your diode truly is a receiver.
A guy told me to use this circuit
BC337.png
on the Q2 use a IR receiver

It works with a led, But with the motor the BC337 fried.
So he said to use a darlington

2N3904 and MPSA13
or
BC548 and BD 139

Moonday I Will buy and test it



In a 'very simple' circuit the LED will respond to normal daylight. Is that what you want?
Yes
Simple is better
More sensible is better too

I was even thinking about to use a LDR, but It would not fit. a 3mm IR receiver fits better


what about a 2N7000 instead, with a 1 M pulldown resistor on the gate?
I dont know How to make a pulldown, Is like that?
2N7000 .jpg

--------------
 

ci139

Joined Jul 11, 2016
776
related reading see Photodiode Tutorial TAB
▲ they have science equippement that is quite expensive and specific -- there's some afordables also:
Wavelength Range λ 350 - 1100 nm
Peak Wavelength λP 980 nm (the red light ends 700nm - so it's iR or near-iR)
there are a lot of problems getting this right and working - such as - daytime direct intense sunlight (may saturate your sensor and trigger it)
the other factors - beam distance focus direction - what they use in TV remotes is modulated infrared pulses that get to iR sensor through proper light filter - and trigger nothing unless the encoded signal sequence matches the expected command - perhaps it not required if your setup is simple enough . . .
 

Thread Starter

Jonasz

Joined Aug 26, 2016
9
Light interference is not a problem, it will stay in the dark inside the bolt chamber on the paintball pistol. the beam distance will be just one inch
 

ian field

Joined Oct 27, 2012
6,540
What he said is that when he replaces the motor with a white LED, the white LED comes on when the photodiode is illuminated. My guess is that there is enough base current to turn on an LED with 5 mA, but not run a motor with 200 mA. If a 3904 can handle the motor current, what about a 2N7000 instead, with a 1 M pulldown resistor on the gate?

ak

ak
The problem seems to be; it works with a LED load - but not a motor. Using a Darlington might possibly fix that. The MOSFET solution could work - but just stating 1M pulldown may not work straight off. There wouldn't be any problem turning the MOSFET on, but compensating for PD leakage due to any ambient light that sneaks in, may take a bit of trial and error.
 

Thread Starter

Jonasz

Joined Aug 26, 2016
9
is there any option to try with the actual inventory?

TIP42
TIP42
2N3904
2N3904
BC337
BC557c
IR sensor
pot 100k
pot 20k
resistance 10k
resistance 1k
resistance 390
resistance 390
 

AnalogKid

Joined Aug 1, 2013
8,138
I dont know How to make a pulldown, Is like that?
Yes. I should have been more clear - a 2N7000 or 2N7002 is a small N-channel MOSFET, almost like the FET equivalent of a 2N3904. To turn it on takes a higher voltage at the gate, but the gate current is almost 0 mA. For a very low current sensor like a photo diode, it might work better than a bipolar transistor.

ak
 
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ian field

Joined Oct 27, 2012
6,540
to play silly smart-S - its like a darlington of two 2N3904 (only slower - muhahahahaa) - so it's more sensitive . . .
Darlingtons are not known for being particularly fast. The only thing that significantly slows a MOSFET is the small magnitude of the photocurrent charging the gate capacitance.
 

MaxHeadRoom

Joined Jul 18, 2013
19,162
to play silly smart-S - its like a darlington of two 2N3904 (only slower - muhahahahaa) - so it's more sensitive . . .
Do you need ultra hi speed?:rolleyes:
Siliconix labeled the original 2n7000 as a 'Fetlington' as it compared to a cross between a darlington with FET characteristics.
Max.
 

ian field

Joined Oct 27, 2012
6,540
Do you need ultra hi speed?:rolleyes:
Siliconix labeled the original 2n7000 as a 'Fetlington' as it compared to a cross between a darlington with FET characteristics.
Max.
With a bare PD; it may be worth considering a voltage follower - you can use a lower G/S shunt resistor for faster discharge of gate capacitance.
 

wayneh

Joined Sep 9, 2010
16,114
Another issue with that circuit is that the motor will respond very quickly to the IR diode signal, which is not debounced. Depending on the application it may make sense to use a 555 monostable to debounce the input and make sure the motor runs some minimum length of time after a signal is detected. Likewise on the input, something like an RC integrator on a comparator input would prevent possible chatter from an occasional flash of light, for instance. And that's another thing, the sudden battery voltage dip when the motor turns on will cause havoc on the PD sensor output.
 

ian field

Joined Oct 27, 2012
6,540
Another issue with that circuit is that the motor will respond very quickly to the IR diode signal, which is not debounced. Depending on the application it may make sense to use a 555 monostable to debounce the input and make sure the motor runs some minimum length of time after a signal is detected. Likewise on the input, something like an RC integrator on a comparator input would prevent possible chatter from an occasional flash of light, for instance. And that's another thing, the sudden battery voltage dip when the motor turns on will cause havoc on the PD sensor output.
AFAICS: the TS hasn't been *EXACTLY* clear on the intended switching mode - but its most likely that its supposed to switch on and off cleanly rather than any kind of linear action. I'd go for an LM358 with one stage as voltage follower and the other as Schmitt trigger.

A non-retriggerable monostable might avoid the need for a Schmitt, but unless they're using SMD parts - a single op-amp isn't any smaller than a dual.
 
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