Build your own diversity controller! - Page 3 - RC Groups
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Jan 15, 2010, 02:27 AM
mkmkmk13's Avatar
call me crazy but how hard would it be if it had 4 Rx to choose from
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Jan 15, 2010, 03:04 AM
Registered User
Not so hard as you can believe.
You may use double contacts relays, and switch the rssi signal together with the video signal.
You need 3 such circuits, cascaded on two levels.
The first level consist of two comparators fed with the 4 RSSI and video streams. Their outputs will be two "winner" video and their respective RSSI feeding the 3rd comparator.
Jan 15, 2010, 11:09 AM
Engineer for Christ
IBCrazy's Avatar
Renatoa is right. Very simple. For 4 inputs simply make 3 RSSI comparators linked as he suggested. You can also use a second relay for your audio channel if you use that. Just solder it right in. It won't affect anything.

Jan 17, 2010, 10:04 PM
Registered User
Thanks to IBCrazy's help in private messages, I've put together a first draft of a printed circuit board for the diversity design. This uses no relay, a straight 5V design, and an BA7654F video switch for both video and optional winning RSSI. One board supports two video inputs. Three boards should support four video inputs.

diversity video switch - schematic

diversity video switch - pcb

This board uses quite a bit of surface-mount stuff, even though all the connectors have to be done with relatively huge through-hole soldering. I could have used socketed DIPs for the op-amps, but most of the video switch chips are only available in the surface-mount variety. I've submitted the board to a PCB fab house (it mostly saves me figuring out if the problems are in the wiring or in the fab itself). I should be able to solder up a prototype within a month.

IBCrazy, if this thing works at all, I'll contact you again about how to proceed with any sales. I'd like to put the final design into Creative Commons, if you don't object. I'm only doing this as a hobby project, but I might solder up a few (or send blank boards) at negligible markup if it turns out to help a few pilots.
Last edited by HariEdo; Jan 17, 2010 at 10:09 PM.
Jan 17, 2010, 10:53 PM
ggtronic's Avatar

thanks IBCrazy + HariEdo
Jan 17, 2010, 11:06 PM
KF5LDN FPV Junkie!!!
Wizzard033's Avatar
Originally Posted by ggtronic

thanks IBCrazy + HariEdo
AGREED!!! THANX INDEED!!! and also for all the other great electronics projects. IBCRAZY you have expanded my electrical knowledge exponentially
Jan 18, 2010, 01:16 AM
Engineer for Christ
IBCrazy's Avatar
If this is just a hobby project, I have absolutely no objections to you soldering up a few boards. After all I posted this thread as a helping tool with the hope that people would build it and enjoy it. The circuit is public knowledge for the benefit of the FPV community. Not everybody has the ability to solder up their own board. Just give credit where credit is due.

If it ends up taking off for some reason, then we'll discuss the details

Jan 18, 2010, 05:35 AM
scolen3's Avatar
I would totally put this into production. If you could sell these at a fraction of the price of the current ones, they would sell like hot cakes. Look at the price of the cheapest diversity controllers, they are usually around a couple hundred bucks.
Jan 18, 2010, 05:43 AM
Registered User
Shhh... some manufacturers could be considered offended and pop here bashing this "inferior product"
Jan 18, 2010, 01:22 PM
Registered User
wedge98's Avatar
I will totally buy one of these. Awesome job with the design.
Jan 18, 2010, 01:39 PM
Engineer for Christ
IBCrazy's Avatar
The only problem with my design is that it requires a bit of hacking. Sure it's cheaper, but that's because it is less complex. This is the reason I don't think it will be a commercial product. This is for the hobbyist, not somebody who wants a premade system handed to them.

Remember you need two identical modules to make this work, or you will need to scale the RSSI's with a potentiometer. This is simple to do and I will provide data on how to do this shortly.

I'm very proud that HairEdo is going to produce this. As an engineer it is always nice to see others benefiting from your works. I plan to maiden a new airplane today. If I do, I will post the video and indicate when the diversity controller switches.

Jan 18, 2010, 02:17 PM
Registered User
wedge98's Avatar
thank you Alex!
Jan 18, 2010, 04:21 PM
Registered User
In less than tree week I will start to sale a kit ( already assembled PCB ) that do almost the same things, exept it will be synchronisation based diversity. There will be 4 input...and no modification to RX required. I'm using it for the last 3 months and it work really great. Vid are comming...

I will sold it directly here and on . It will be paypal only transaction.
I'm currently waiting for the first PCBs from my PCB supplyer.

here are pics.

It will have 8 leds outputs that allow you to add leds to see where there is a signal, and what signal is used.

The board will be a 2 layers surface mount Ic, RoHs compilant with gold plated pad for a high quality board. Its really small, 2.35" by 3.4" and have 4 mounting hole ( 0.150" ) .

The price will be around 60$US all IC soldered in place, you just have to route your video signal thru a regular servo wire ( included ), this is to minimize the space of somebody who dont want to have 5 full size RCA cable in is wallet.
Jan 18, 2010, 05:05 PM
Registered User
Freakazoid's Avatar
60 bucks for a 4 port oracle aint shabby!
Ill keep it in mind for someday upgrading.
Because ofcourse aside from the switcher youll need 4xRX and 4x antennas.
Jan 18, 2010, 05:07 PM
Registered User
Only one Rx are needed, but, then its usless, but it will work with 1 to 4 rx connected.

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