Foxhunt Transmitter Build #2 - Arduino + Relay

[@seniorchief48]

Great information for me being new to this type of electronics. Wired from 5v into the relay across the coil.

[@kennylyons2835]

I just made this by completely eliminating the relay and the diode. Works fine, code doesn't even need to be changed . 🤷🏼‍♂️

[@fish7days]

I want that shirt !!!!! Great vid, thx. I might just do this.

[@TallTexasGMan]

Thank you for the informative video. It seems to me though that you could eliminate the 5V micro relay from this circuit and simplify it to use a resistor, transistor, and a diode. From the schematics I have seen online the Baofeng radios essentially use the same arrangement as an Icom, except the Baofeng supports an upper and lower band transmit with two separate PTT buttons. I could be very wrong here, just seems like it should be easier than using the relay.

[@KrzysztofStrug]

I wonder why use the relay here, transistor itself will not be sufficient to switch on PTT? Thank for great video 🙂

[@adamrobson4013]

Where is the diode meant to connect please? From the relay coil (white wire side) back to itself on 5v input to relay coil?

[@plproductions8887]

Hi do you have a DTMF CODE? and is there a way of making this with a Nano board?

[@seniorchief48]

Red Summit has a board showing a DTMF wire run to the A0 pin.

[@jakesheffey9256]

A Nano is a much better use for this than the Uno.

[@GM6DX]

Hi, Will the red summit RF's build code ( ie include DTMF) work with your physical design? also can you advise if the relay should click and then stay active for as long as it's powered? ( as mine appears to click and stay active when powered) thanks Billy

[@transmittinguntilrobotsrep1045]

Hi Billy - The use of DTMF should be fine. I remember messing with it for awhile and it did work, but I just wanted to keep the code a bit cleaner for simplicity sake. I'd have to look at the code to see if all of the Arduino pins matched up exactly, but if not, it would be a simple change in the code from one pin to another. As to the relay: Power is always applied to the relay, however it can only form a complete circuit when voltage is applied to the base of the transistor. The transistor, when activated with a voltage, connects the emitter and collector sides and allows the applied power to the relay to complete a circuit back to ground. When the relay is activated, you hear an initial click and the radio should start transmitting. At the end of the programmed code, it should disengage the voltage/current to the transistor, which disengages the path to ground for the relay, which disengages the transmission of the radio. I've found that the use of a relay tends to be very prone to the magnetic fields of the radio and can be easily tripped. Additional ferrites and/or spacing is needed to minimize the effect. I did build a version of this that used optocouplers and it worked without any issues whatsoever, but just haven't gotten around to making a video of it yet. Good luck, and let me know if you have other questions- AC3DS

[@AndrewMurphy8383]

@@transmittinguntilrobotsrep1045 it would help if you did speed the deal to fast so we can see what you doing

[@28bond815]

The parts list shows a diode but it’s not listed on the diagram. Where does the diode go?

[@transmittinguntilrobotsrep1045]

Good catch, sorry about that. I've added an image in the documentation, and will update the diagram soon. The diode straddles the inductor in the relay. You can see this in the video around 5:25 . Thanks for letting me know! I'm going to release another build soon that addresses how to do this with an optocoupler.

[@the1spyderryder]

Please tell me WHY you are using a relay to key a battery operated radio transmitter.

[@chrisf1165]

Congrats. Excellent video. De N3MLB

[@transmittinguntilrobotsrep1045]

Thank you very much!

[@billygm6dx720]

Ok, So the relay clicks and when the transistor is not getting a signal from pin 7 (1k resistor) the circuit is broke. I have ordered a Baofeng as my last one broke so cant test with the handheld just now, is there any way of testing to see if pin 7 is stop supplying without the actual radio?

[@transmittinguntilrobotsrep1045]

That is correct. As soon as the output on pin 7 ceases, the connection between the collector and emitter is broken and the path to ground for the relay is cut, which puts the relay switch back to the off position. There are a few ways that you could test to see if Pin 7 is on/off. First, you could use digitalRead and Print functions to show the status on the Serial Monitor. Alternatively, you could put an LED in line to visualize it.

[@GM6DX]

@@transmittinguntilrobotsrep1045 I have connected an LED on pin 7 and GND. The LED remains lit does not go off and doesn't blink, just stays a solid colour whilst powered. Does this sound like a code error rather than a physical connection? Update: I have used your code and the LED stays on for a few seconds. Then goes off for several seconds and then goes back on. When connected to pin 13 you can see the morse. So your code appears working. 2 questions 1. I have attempted to add / to the string on line 16 and 17 however it will not recognise the / character (for / beacon) 2. Are you cable to modify the code for DTMF to turn in on and off via DTMF. This is a licence requirement in the UK for these beacons ( to turn it on and off via remote) Thanks

[@transmittinguntilrobotsrep1045]

@@GM6DX I haven't looked at the code in a little while, but will do so to see if I can figure out a way to account for the stroke character. Adding the DTMF will probably take me a little bit longer, but using the existing code as the source will expedite that considerably.

[@GM6DX]

@@transmittinguntilrobotsrep1045 I can get a slash by changing a letter or a number not in use example change the 0 to "21121" and it works but If I add the / it doesn't recognise it

[@theonlymango1620]

mine is just keying out for about a min with no tones or morse. then going off for about a min. Then keying out with no tones or morse again. any suggestions?

[@HuisHuis-o4v]

I seem to have the same conundrum

[@the1spyderryder]

I dont understand why people doesn't use the replacment microphone cable that you can buy from Amazon for a few bucks. I also don't know why everyone who copies this plan doesn't use a transistor to key the radio instead of a relay.

[@kennylyons2835]

In my case I don't know how and I'm building someone else's plan. Though mine will have a slight modification I don't know how to replace the relay with a transistor, maybe one day.

[@billygm6dx720]

Can you update your code to include DTMF?

[@transmittinguntilrobotsrep1045]

Yes, that will give me a good reason to get back to the workbench and hammer out some code.

[@GM6DX]

@@transmittinguntilrobotsrep1045 Brilliant thank you