Wayne Dowler

The "Caller's or Leader's" radio circuit

Recommended Posts

Got a question for all you experienced electronics buffs:

Several years ago, we had an article on how to make a caller's circuit. Came with a diagram and I think some pix. It was designed to lock the caller's radio in transmit mode and had a plug in to mix music into it. The result works pretty well. 

Here is my question:

Many of us have gone to using a Bluetooth speaker for the music. It can  be aimed at the line and also provide a "home" for the team's movement. So - the question is: Can the circuit be made smaller, with no extra wires? Just a plug for going into the radio and a plug in for your headset and whatever needed electronics in between?  Something say 6" long or so, instead of the tangle of wires we have now? 

Disclaimer: I have no electronics background, just experience using them with my teams. I'm looking for a "cleaner" setup over what we use now. Don't know if it is possible or ...?? ANYONE??

Share this post


Link to post
Share on other sites

This is a cool question...for those of us who don't know what you are using now can ya post more info or link to a past discussion?

Sent from my Moto G (5) Plus using KiteLife mobile app

Share this post


Link to post
Share on other sites

A couple of thoughts on this overall:

I really encourage the use of good rechargeable batteries, instead of the provided battery packs. I use Uniden radios and found a 12 pack of "AAA" rechargeables and a good charger for them on Amazon. Why? I looked on the battery packs and found that they were about 1/2 the power of the rechargeable ones. Mine uses 3 "AAA" batteries, Midlands use 4 "AA" batteries. The leader of one of the teams I'm on, uses the high power rechargeables and his radio easily lasts all day calling. On the line as a listener, mine last for several days. With a 12 pack, I always carry an extra set with me - just in case mine die! 

Anyway my original question is-can someone shrink this circuit down way smaller to just a plug in for the radio, electronics needed, and a plug for the headset, eliminating the music mixing wire and plug??

Share this post


Link to post
Share on other sites

 

15 hours ago, Wayne Dowler said:

Anyway my original question is-can someone shrink this circuit down way smaller to just a plug in for the radio, electronics needed, and a plug for the headset, eliminating the music mixing wire and plug??

The circuit looks like a custom Y splitter. I see a 2.5mm stereo male connection, a 2.5mm female, and a 3.5mm stereo male connection with optional volume adjustment.  Looks like something I'd put together trying to not spend any money.

I'm not sure if you're concerned about size and still want the Y splitter, or if you're looking only for a headset.

 

If you're looking for size for the and you're comfortable with a soldering iron you could make that circuit as small as you want. I imagine you could attach the three directly with jumpers and wrap them in tape for a tiny 3-way adapter. 

For off-the-shelf parts, you could piece together a short 2.5mm M/F/F cable plus two small adapters to change the size and plug gender.  Any of those could be replaced with a longer cable if you need.  There are cables with inline volume control, if you want that too, or not.  If you've got a A/V wholesale store nearby, they've probably got bulk bins of those parts for even less money, make a chain of adapters for cheap.

 

Or, if you're asking about alternatives to broadcasting to the older style radios...

If people have bluetooth headphones (which are becoming common thanks to Apple) you could use your a bluetooth headset or bluetooth microphone to send to an inexpensive bluetooth receiver which outputs to 3.5mm, then use this thing  to broadcast four bluetooth signals.  That's one broadcaster, four receivers, and a little wireless bundle you could keep in a waterproof bag. 

Share this post


Link to post
Share on other sites

Sorry all the Bluetooth stuff is undependable and very expensive. Not sure on battery life either or how it would hold up under the conditions usually found. Plus there is no discrimination of units. If anyone says anything they will drown out the caller, Every Bluetooth unit is open to both listen and receive. As you noted, the original circuit is inexpensive and has no power requirements. Right now, if you are "on" using the same channel, and there are 2 radios locked in transmit, there will be feedback. This is easily dealt with, by one party switching channels.

What I was asking is can the "splitter" idea be eliminated, get rid of the music mixer,  and enough electronics  kept, to just lock the caller's radio in transmit mode?  Just the plug going into a radio and a plug in for the headset, and the needed electronics in between, and make it as short as possible. Sort of like locking the VOX circuit open - but full time.  See, the VOX feature on radios, leaves much to be desired. The circuit to transmit with VOX, usually opens about halfway through your command. Meaning your line mates miss out on a bunch of the commands. I know because using a  different brand, has forced me to use the feature - it is not a viable solution. VOX was an example, not how it worked in reality. 

Having just one leader's radio locked open to transmit, with the least amount of hanging stuff, is the idea.

 

Share this post


Link to post
Share on other sites

Undependable. Many radios have shapes that don't allow a good tight fit. Or like my Unidens that have the headset jack directly across from the transmit button. Last thing you need is your caller to have their radio go dead during a routine, because the band slipped or broke.

There is nothing "wrong" with the circuit as presently constructed, just looking to see if it can be modified somewhat. Eliminate an unneeded function and shrink the overall size.

As I mentioned, I have 0 electronic background, and my stroke makes me dangerous with a soldering iron in my hand. 

Share this post


Link to post
Share on other sites

One option would be to lose the radio receivers, except the caller's. Plug bluetooth transmitter into caller's radio. Rest of team uses bluetooth headphones. The transmitter can be had for around $30 and about the same for each headset. Most will tx/rx for about 12 hours on one charge.

Share this post


Link to post
Share on other sites

Three parts:

----- On Bluetooth concerns

Battery life is long, Apple's headphones last about 5 hours on a charge, the transmitters and receivers mentioned above last about 10 hours, and the parts can be kept in a ziplock bag safe from the elements. All of them recharge quickly. 

You're right that they can be fiddly since each Bluetooth device is paired in a 1:1 setting instead of an open broadcast, and batteries need to be recharged when they're dead rather than swapped out. Range is very short compared to the handheld radios, and others on the field are also likely to have one you can borrow if something goes bad.

----- On why the circuit helps keep VOX transmitting.

I'm not sure, but I think the handsets are forbidden from having a constant broadcast mode. They have a voice activated transmit (VOX) so they can keep you from continuously broadcasting. Wrapping an elastic band around the push-to-talk button wouldn't work because many handsets have a secondary timeout to prevent constant PTT broadcasting.

I think that's why the audio input for your music is important in that solution.  If you have your music playing in the input jack it will always keep VOX satisfied that you're talking.  That specific model doesn't have a VOX timeout, so at transmits as long as your song keeps playing.

If you don't have music playing then VOX will not detect speech and stop transmitting. It can take time for VOX to start transmitting, and receivers that have an auto-squelch mode can take time before they play the audio.  You can increase the sensitivity of VOX so it might take less time to start transmitting. You can also turn off auto-squelch mode if you don't mind hearing static. Doing them both would make it better, but still wouldn't be perfect because VOX would still need that time to detect something. It might be able to pick up the music in the background, but there's no way to be sure without the audio splitter.

----- On a cheaper, wireless Y cable

To guarantee that VOX stays active you need the Y splitter with music playing.

The original circuit includes a small capacitor and resistors. They are present because the microphone requires power to operate, but your music line (phone or walkman) doesn't need that power. You can plug directly to other audio sources, but it may mess with the microphone's power levels. That can mean quieter microphone sensitivity and can shorten the microphone's life. Exact details will depend on the hardware being used.

The 3.5mm splitters are cheap and tiny if you shop around, if you've got a Fry's nearby you can probably find some for cheaper. Otherwise, $3.09 at amazon. Assuming a 2.5mm mic jack you'll need adapters, probably one for your headset mic into the splitter, and one for the splitter into the handset's mic jack. That's $5.18 at amazon for the pair.  They all plug directly in to each other, no soldering, no cables.  You still need the cable from your headset and from your phone (or walkman) but you can shop around for those cable lengths.  

That's $8.27 and waiting for shipping. It also assumes you've got the radios, they're another $90.   An all-bluetooth system costs about $150 if people already have their own hip-and-trendy iphone AirPods. The $50 cost difference is relatively minor when you consider there are $1500 worth of kites in the air, plus likely another $4000 for each pilot's quiver of different vented kites and other gear.  I'm with you on saving money, I don't have enough to buy the things I like, but in the grand scheme of the sport headsets are relatively cheap.

Share this post


Link to post
Share on other sites

If you take two plastic cups and stretch a string between them . . . . .        😂

Share this post


Link to post
Share on other sites
24 minutes ago, makatakam said:

If you take two plastic cups and stretch a string between them . . . . .        😂

Only works if you can put the string through the heads of those in between the caller and tailgunner!

I think this got off track: Let me get back to some ideas or at least what I know:

This all was done several years ago as an inexpensive way to have good communication with all parties on a line - no matter how big it gets. We have used this in small teams, right up to the last giant grid formation of 81 (9x9) pilots at WSIKF! It is easy for a team to collectively change to a different channel, if the one selected is being used. 2 circuits open on a single channel cause feedback and neither line hears anything. So one team switches to an unused channel and everyone is happy. This also works great if you ground crew for a team. Many times I dial in the channel of the team flying and the leader can talk to me if there is a crash. Also at some festivals, the announcer can also dial in and put the radio next to the mic and let everyone listen in to the calls made. It does work effectively, I'm not questioning that.

The circuit as constructed works to open the transmit function, whether you have music  going through it or not. That was my original question: could we could lose the mixing part, still lock the radio in transmit, but shorten the thing down.  As constructed, most of these circuits are too long, especially if you no longer use the mixing part. It's a pain to put in a pocket or let dangle - just too much.

Midland radios seem to have a proprietary 2 prong plug in - I'm guessing that one is for transmit, one for receiving. The circuit as made now uses just one side. The leader only wears a headset for calling commands to the rest of the line. The rest of the line uses the channel selected and closes any VOX setting. This way only the leader's headset is live. Everyone else is listening to the calls.

Because of the 2 separate circuits, Midlands seem to be the leader's radio of choice. I have Unidens, I like the limited menu tree and layout of controls, but because of the single input, the circuit doesn't work for me. I have used the VOX feature on them, no matter how sensitive I set them, they always seem to open and close and cut my commands off somewhere. This is not a good option - period.

So back to the original idea - to all you electronic buffs - can the circuit as described in the original article - be altered to still lock the transmit circuit open, but lose the mixer and overall shorten it?

Share this post


Link to post
Share on other sites

Thanks, that helps.

The circuit only locks the transmit open through happenstance when music isn't playing. The VOX switch should turn it off when nothing is coming through. The fact that it remains transmitting means there is electrical noise from the loop, which changes the DC bias. It is supposed to keep the powered side and the non-powered side from having issues, but it ends up adding electrical noise that confuses the VOX chip.

You could leave that wire out entirely, keep the electrical loop with the resistors and capacitors. They can be as small as you're able to manipulate, probably just a few centemeters then wrapped in tape if you'd like, giving a small adapter about the size of your fingertip, that plugs directly inline. Here's the parts, more or less:

image.png

A plug and a (sketched-in) socket,  two resistors, and a capacitor. No wires are needed. You could trim them down and create a tiny little bundle, wrapped in shrink-wrap plastic or even wrapped in electrical tape.

You could also create a two-socket version and use it for your audio input line. There is no need for the wires. That would be exactly like the original, except without the wires:

image.png

This works because there is a dedicated mic jack for that model, and that model detects the electrical noise as enough talking to trigger VOX.  If you use a different radio that has a single jack for microphone and speakers then you'll need to split that out first.  Also, a different radio might not trigger the transmit from the electrical noise. 

Share this post


Link to post
Share on other sites

My only question is - even though the caller's VOX circuit is off too? I'm not 100% sure on how the radio is set up, but I don't think they are using the VOX circuit.

Share this post


Link to post
Share on other sites
22 hours ago, Wayne Dowler said:

Only works if you can put the string through the heads of those in between the caller and tailgunner!

No, no, no. You duct tape a cup to each flyers head and run the string between them. Then you have one person at each end of the line pulling the person on the end to keep the string taut.

  • Like 1

Share this post


Link to post
Share on other sites

For those that don't have the circuit - here is one possible solution - especially on small lines:

I'm looking into a voice amp, similar to those used by tour guides or professors in lecture halls. Comes with a headset ( wired or bluetooth), a small amp/speaker, and a strap. Speaker can be clipped to the belt or pocket, worn over the shoulder, or around the waist, depending on how you configure the strap. Also can be used as a speaker for your device. Many models on Amazon.

One of my teams uses one and easily carries down the 4 person line, sometimes 5 or 6. Not sure how many deep it will carry ....... but it might be an alternative ....?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now