Hi,

I have an old film camera that has a 2.5mm jack input which you can use to plug in a very simple ON/OFF switch to trigger the camera shutter, it is basically two wires that when connected together the circuit closes and the motor turns on. The camera motor operates with 7.2v DC. I was wondering if there is a way to turn this switch into wireless. I saw a few wireless remote control devices on Amazon such as this one, but I am not sure if this could work.

Does anyone have any idea if this could work? or if I should be looking into something else?

Thank you so much!

 

Does anyone have any idea if this could work?

I think it may, but one review stated it had about a half second delay between pressing the button and its receiver operation.
That may not be acceptable for camera triggering.

 

A wireless doorbell might be a candidate for a solution.

 

I think it may, but one review stated it had about a half second delay between pressing the button and its receiver operation.
That may not be acceptable for camera triggering.

Thank you, I might give it a try and see it works.

 

A wireless doorbell might be a candidate for a solution.

What type of wireless doorbell? I forgot to mention, that I would need the circuit to be small. I have a feeling that most of those wireless doorbells could be quite bulky.

 

I would say that is a good start but as it exists, would have concerns.
The device you mentioned is using a MOSFET to "drive" the two (+/-) outputs.
Your camera is looking for a simple mechanical on/off switch.
Without having detail schematics of wireless device and camera, had to say if it WILL work.
That said, if you add a simple mechanical relay then you don't need to know as much.
The wireless device would drive the relay's coil and the relay contacts would connect to camera.
Relay example:
https://www.amazon.com/Omron-G5V-1-...1&s=industrial&sprefix=5v+relay,aps,62&sr=1-1

 

I would say that is a good start but as it exists, would have concerns.
The device you mentioned is using a MOSFET to "drive" the two (+/-) outputs.
Your camera is looking for a simple mechanical on/off switch.
Without having detail schematics of wireless device and camera, had to say if it WILL work.
That said, if you add a simple mechanical relay then you don't need to know as much.
The wireless device would drive the relay's coil and the relay contacts would connect to camera.
Relay example:
https://www.amazon.com/Omron-G5V-1-DC5-Electromechanical-Single-Through/dp/B00UMA4YY6/ref=sr_1_1?content-id=amzn1.sym.ea945d40-8e84-42be-ad5c-249b9bca6a40:amzn1.sym.ea945d40-8e84-42be-ad5c-249b9bca6a40&crid=1J95FZ68AY35T&keywords=Relays&pd_rd_r=baca49ab-79ae-4021-aeab-409ac8bcbb9b&pd_rd_w=VTuYq&pd_rd_wg=HQzdH&pf_rd_p=ea945d40-8e84-42be-ad5c-249b9bca6a40&pf_rd_r=C9FCF0078KBFCVY5X2SG&pid=si6x41a&qid=1681917776&refinements=p_n_feature_eight_browse-bin:18644647011,p_n_feature_nineteen_browse-bin:18945450011&s=industrial&sprefix=5v+relay,aps,62&sr=1-1

Thank you @wraujr , I think that could be the solution.

I was able to find this diagram from the camera, it is in French but it is easy to understand. This is a camera from the 60s-70s, mostly all the controls are mechanical.

The switch in question that I am trying to convert to wireless goes to the connection labelled "C de a distance" which means "C from remote" not sure what the C stands for. I hope this helps.



Regarding the wireless device from Amazon, I could not find any info aside from the fact that someone mentioned that might not work with high currents.

By the way, shouldn't the relay be SPST? instead of SPDT?

 

Wasn't sure whether you needed NO (normally open) or NC (normally closed) contacts.
SPST would provide NO. SPDT would give you option of NC or NO depending on connections.
From your schematics, NO looks like what you need so SPST relay would work....

 

Wasn't sure whether you needed NO (normally open) or NC (normally closed) contacts.
SPST would provide NO. SPDT would give you option of NC or NO depending on connections.
From your schematics, NO looks like what you need so SPST relay would work....

Thank you!

 

It looks like pins +/- are supply to the wireless module.
Looks like P+/P- are the "outputs" that would connect to relay.
Note that + and P+ are connected together (let's say that's positive terminal of 4.5V, 3 AAA batteries)
Then P- is switched to - (aka GND).
My take is that connect 5V (i.e. 4.5V from 3-AA) to + and - terminals.
Then relay coil to P+ and P- noting that P+ will always be active and P- will connect coil to GND when activated.

 

The wireless remote control you linked to might work, but it depends on whether it can be configured to output a signal that will trigger the camera's shutter release. You may also need to ensure that the remote's output signal is compatible with the camera's input signal. Another option could be to look for a wireless remote specifically designed for your camera model, if available. Alternatively, you could try building your own wireless remote using a microcontroller or a Raspberry Pi, but that would require some technical know-how.

 

If you do a Google of "wireless relay board" you will find similar to what you posted but using a relay rather than mosfet. They are very common using a key fob transmitter and one to four channels. Most I have used offer decent range too. Most also have a jumper so you can setup momentary or latching. Momentary meaning the relay (switch) is active only while the button is held.

Ron

 

So basically something like this?

 

Yes, that is what I was thinking.

 

Thank you!

By the way, I am building a power bank for this camera from which I would be tapping into the wireless module. The outputs I have are 3.6v, 7.2v and 12v. I can try either of the three with this wireless module, although perhaps the 7.2V would be ideal.

But I have never tried a relay before, so I am not even sure how to identify or find the correct one for this application.

In terms of contacts, I know it needs to be SPST, but in terms of application, this needs to be a general purpose, not a protection one, right? And in terms of operation, is this an attraction or induction relay? Then I am not even sure about the voltage ratings, it needs to work for DC voltage but aside from that I am lost. I apologize in advance because I am a hobbyist and like I said before I have never used relays so I am not even sure if I used the correct terms.

 

The relay I gave you has an 80% minimum coil voltage to operate. @5V that would be 4.0V and you are running 3 AA that might be on the low side, especially as they drain. On reflection, I might go with a 4-AA alkaline battery solution that give 6V (initial/fresh batteries). On the relay coil, its 5V at 30ma, so we need a 1V @ 30 ma current limiting resistor on the coil or 33 ohm.

 

I would go with the 7.2V output (3.6V too low for wireless module)
That changes coil current limit to (7.2V-5.0V)/30mA = 73 ohm (75 ohm, 5%).
Also, add 1N4001 diode in parallel with coil for reverse voltage turn off protection of MOSFET.
Here's data sheet for one I found on Amazon... (Omron G5V-1-DC5)
https://omronfs.omron.com/en_US/ecb/products/pdf/en-g5v_1.pdf
In your case the transistor, is the MOSFET on wireless board.

 

1V @ 30 ma current limiting resistor on the coil or 33 ohm.

Thank you for all the info!

I actually might be using that battery pack I mentioned earlier, and I fear the output current would be higher than what the typical AA alkaline batteries provide. It could be 3500mAh or higher depending on the cells I end up settling with. Is there a way to provide a consistent 30mAh no matter what the input current is?

 

No need to worry (you are not understanding current). A battery supplies a mostly constant voltage and the current varies depending on how much your circuit needs. The resistor for the coil is because you are supplying more voltage (7.2V) than the coil requires (5V) and you must "drop" the 2.2V difference while having the coil use 30ma (hence 2.2V/30ma = 75 ohm).
The coil does not use 30mAh (that is mA-hour), it uses 30mA. If you kept the coil powered on for one (1) hour it would use 30 mAh of your battery's capacity (3500 mAh). Pay close attention to units.

 

You are right, thank you! I just got confused for a moment. And I guess I can use that SPDT relay then. Something like this?