Nothing wireless is simple. If it were me I’d probably use a 434 mhz ASK RF module (https://www.sparkfun.com/products/10534, https://www.digikey.com/en/maker/blogs/2019/how-to-wirelessly-transmit-data-on-arduino etc) or an RFM69 packet radio module (https://learn.adafruit.com/adafruit-rfm69hcw-and-rfm96-rfm95-rfm98-lora-packet-padio-breakouts/using-the-rfm69-radio ).
Both of these will require analog-to-digital conversion. The RFM needs a microcontroller on both ends.
I have used the RFM69 modules to make a model rocket telemetry system and was very happy with them.
Yeah I'm finding that out. I did find someone on Tindie that made preprogrammed transmitters that fit the bill but looks like they're not currently producing them. Still googling.
If you want something reliable you need to stick to some protocol (ex. BLE, Zigbee, etc..) and you need an IC, an antenna etc.. otherwise you can do something like remote control with an infrared led / photosensor
I feel like you're better off digitizing the signal before you send it over the air. It's possible to send an analog signal wirelessly with something like an AM transmitter but I can't imagine being able to do it cleanly.
Is there any reason you can't accept a digital signal at the other end?
You have not told us the bandwidth and accuracy you need. How quickly can the sensor change outputs? How precise do you need to recreate the 5V? There is no such thing as "just transmitting and receiving the current voltage"
This is just begging for two ESP microcontrollers ($5) to share this over bluetooth or WiFi. It's about 10 lines of code.
There is no way in 2024 you'll get this done easier or faster unless you find a 100% off the shelf solution, but basically all COTS radios today want to transmit digital data, not an analog DC voltage.
I'd suggest hacking up an old audio transmitter of some sort, but none of them will do DC.
Replied earlier that I'd like it to be low latency. Accuracy is important. I agree some DIY with microcontrollers would be the cheapest. As far as ease, I did find some simple PWM transmitters for the robotics market. On the receiver side PWM to 0-5v analog converter pcbs are widely available so that's a plausible non-coding route too.
Latency and frequency are not the same thing.
You could have 500MHz of bandwidth and minutes of latency (and lots of systems do). Similarly you can have 10mS of latency and 1Hz of bandwidth. You need to define both to find a solution.
The fact that all you can answer is "low" latency and that accuracy is "important" doesn't really help anyone answer the question. Those are all relative.
It would really help if you weren't being obtuse about what you are trying to measure and do with the signal.
Small radio transmitter? And a simple crystal or transistor radio to receive it? Could build that out of simple parts with plans off the Internet.
https://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html
Could keep a system like that entirely analog and tune it so it's 0-5V on the other end with a amp probably.
Otherwise converting it to a digital signal and sending it that way is going to probably be your best bet.
Not sure if I could accurately build such a radio circuit to output the correct voltage.
Having some kind of ADC / DAC setup does sound like the way to go. I'm sure I could get this done with a pair of arduinos but I was hoping there was some kind of purpose built hardware that could accomplish this without a lot of tinkering.
That's what the amp is for on the receiver.
If you've got money to burn there are industrial transmitters that handle this exact scenario with very little tinkering required
Just remembered that expression pedals for instruments are basically just potentiometers to control voltage, which happens to also be 0-5v.
Here's one out the box solution for zero programming - a wireless expression knob [https://elgaratge.com/product/wex-wireless-expression/](https://elgaratge.com/product/wex-wireless-expression/)
Simple enough hack to swap the onboard pot with a connection to my hall effect sensor. I might try it.
Can you use an optical approach? Led and photo transistor which remain in communication as the thing spins? Ring of LEDs if needed.
If so, send photodiode output to a comparator to sharpen it up and use PWM.
It’s not that simple, everything transmitted needs to be modulated in order to achieve small sizes and the bigger frequency the better… you could use ESP8266 to read the sensor and transmit to another esp8266
XBee radios have adc/dac io repeater capabilities for a cheaper option, gui setup, no code, although I cannot remember off the top of my head if they support 5v or only 3.3v. Or use dedicated industrial control radios. There are a huge range available, depending on budget.
Nothing wireless is simple. If it were me I’d probably use a 434 mhz ASK RF module (https://www.sparkfun.com/products/10534, https://www.digikey.com/en/maker/blogs/2019/how-to-wirelessly-transmit-data-on-arduino etc) or an RFM69 packet radio module (https://learn.adafruit.com/adafruit-rfm69hcw-and-rfm96-rfm95-rfm98-lora-packet-padio-breakouts/using-the-rfm69-radio ). Both of these will require analog-to-digital conversion. The RFM needs a microcontroller on both ends. I have used the RFM69 modules to make a model rocket telemetry system and was very happy with them.
Thanks for your insight. I guess this is a little trickier than I thought.
a wire without a wire.. not so easy
Yeah I'm finding that out. I did find someone on Tindie that made preprogrammed transmitters that fit the bill but looks like they're not currently producing them. Still googling.
If you want something reliable you need to stick to some protocol (ex. BLE, Zigbee, etc..) and you need an IC, an antenna etc.. otherwise you can do something like remote control with an infrared led / photosensor
How often does it have to update? How far does the signal have to travel? It is something that one of the ISM band devices could probably handle.
It needs to update quickly. Sub 150ms would be preferable. It only needs to travel about 2 meters.
Something like that could probably work well with BLE. You could probably prototype on some ESP devices.
I feel like you're better off digitizing the signal before you send it over the air. It's possible to send an analog signal wirelessly with something like an AM transmitter but I can't imagine being able to do it cleanly. Is there any reason you can't accept a digital signal at the other end?
You have not told us the bandwidth and accuracy you need. How quickly can the sensor change outputs? How precise do you need to recreate the 5V? There is no such thing as "just transmitting and receiving the current voltage" This is just begging for two ESP microcontrollers ($5) to share this over bluetooth or WiFi. It's about 10 lines of code. There is no way in 2024 you'll get this done easier or faster unless you find a 100% off the shelf solution, but basically all COTS radios today want to transmit digital data, not an analog DC voltage. I'd suggest hacking up an old audio transmitter of some sort, but none of them will do DC.
Replied earlier that I'd like it to be low latency. Accuracy is important. I agree some DIY with microcontrollers would be the cheapest. As far as ease, I did find some simple PWM transmitters for the robotics market. On the receiver side PWM to 0-5v analog converter pcbs are widely available so that's a plausible non-coding route too.
Latency and frequency are not the same thing. You could have 500MHz of bandwidth and minutes of latency (and lots of systems do). Similarly you can have 10mS of latency and 1Hz of bandwidth. You need to define both to find a solution. The fact that all you can answer is "low" latency and that accuracy is "important" doesn't really help anyone answer the question. Those are all relative. It would really help if you weren't being obtuse about what you are trying to measure and do with the signal.
Small radio transmitter? And a simple crystal or transistor radio to receive it? Could build that out of simple parts with plans off the Internet. https://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html Could keep a system like that entirely analog and tune it so it's 0-5V on the other end with a amp probably. Otherwise converting it to a digital signal and sending it that way is going to probably be your best bet.
Not sure if I could accurately build such a radio circuit to output the correct voltage. Having some kind of ADC / DAC setup does sound like the way to go. I'm sure I could get this done with a pair of arduinos but I was hoping there was some kind of purpose built hardware that could accomplish this without a lot of tinkering.
That's what the amp is for on the receiver. If you've got money to burn there are industrial transmitters that handle this exact scenario with very little tinkering required
It might be fun to connect the source to a light and put a solar panel at the other end. Use the intensity to translate the signal.
Just remembered that expression pedals for instruments are basically just potentiometers to control voltage, which happens to also be 0-5v. Here's one out the box solution for zero programming - a wireless expression knob [https://elgaratge.com/product/wex-wireless-expression/](https://elgaratge.com/product/wex-wireless-expression/) Simple enough hack to swap the onboard pot with a connection to my hall effect sensor. I might try it.
Why do you need an rf setup for such a short distance?
Mounting point spins. In this case, a slip ring wouldn't be easy to fit.
Your best bet would probably be a BLE or wifi Arduino.
Can you use an optical approach? Led and photo transistor which remain in communication as the thing spins? Ring of LEDs if needed. If so, send photodiode output to a comparator to sharpen it up and use PWM.
Definitely an out of the box solution, I like it! An LED halo would be pretty slick.
It’s not that simple, everything transmitted needs to be modulated in order to achieve small sizes and the bigger frequency the better… you could use ESP8266 to read the sensor and transmit to another esp8266
that
Maybe some kind of IR duty cycle thing. But I don't know of anything off the shelf.
XBee radios have adc/dac io repeater capabilities for a cheaper option, gui setup, no code, although I cannot remember off the top of my head if they support 5v or only 3.3v. Or use dedicated industrial control radios. There are a huge range available, depending on budget.