TTL Buffer Suggestions

[mikkojay]

Calling all engineers!
I am in the process of assembling what will be a long-range remote control keyboard. I found a couple of nice 6 channel rx/tx pairs on ebay:


The output is momentary TTL, like if you press and release channel 1, pin 1 will go hi/low for as long as you hold the button.
I plan to interface 2 of these to a pcb that has been "hacked" from a standard usb keyboard.
Here is the general idea of the keyboard's pinout, it is a typical keyboard matrix:


What I am looking for is a suggestion on a TTL buffer chip to use in order to tie the two together. I need to be able to keep the X and Y lines separated.
I guess the ideal circuit would use, for example, X1 as input, Y1 as output, and would be gated "on" when channel 1 TTL on the receiver board goes hi/+5.
Does that make sense?
I also had the option to buy a version of the board that included a relay for each output channel, but I thought that might induce a little bit of lag, plus the fact that they were a little more expensive.
Shouldn't be too tall of an order right?
I thought I would ask the technical resources here before scouring the net for alternatives.
Any ideas would be appreciated!
Thanks, Mike

[marconi]

You can do it on the cheap just using simple diodes, or
maybe employing an OR gate...
With the diodes all your looking for is isolation.
I'd try the diodes first..I do that all the time for transmitter control circuits,works and easy to fix.
Dunno, maybe someone has already done what you are attempting and will chime in.
Sounds like a good project.

[mikkojay]

Cool- maybe optoisolators might be nice too.
I'll have to dig around the junk drawer and see what I can find.
A chip with 6 of these on it would be pretty tempting:

If I get something usable after the smoke clears, I will be sure to post the details.
-Mike

[mikkojay]

Hey, I received the parts in the mail yesterday.
I ended up using some 2n5060 scr's since I had a bag of them in my parts box. I ran a 220 ohm resistor off each output to an LED so I could watch the outputs toggle. This all works just great, but I am on to my next issue: The two transmitters/receivers conflict when both are pressed simultaneously!!! The solder "dip switch" bank (that sets a custom freq. for each rx/tx) is currently only different by 1 hi/lo byte, so maybe if I flip all on one of them, maybe I will get enough frequency difference between the two pairs to avoid conflict. They work fine independently, but when you transmit both simultaneously, neither works.
Man, if it isn't one thing, it's something else...
I'm not giving up yet, next will be an email to the manufacturer.
Later, Mike

[mikkojay]

Dang, you know what- I think that since these are both AM 315mhz, I may have an unavoidable conflict. The manufacturer allows selection of 315 or 433 mhz, so in retrospect, I probably should have ordered one of each freq. Anyway, I ordered 2 more of the other freq. since they are only 12.50 USD each. More waiting by the mailbox I guess...
-Mike

[marconi]

Glad you got something figured out..
I think I'd keep trying different dipswitch settings one one pair
maybe you could get it on a different frequency.
433Mhz may not be a good choice as this is right on in the 432Mhz Ham band
Many hams use high power (up to 1kW) and this may drive you up a wall when it receives one of these transmissions.
I cant believe a manufacturer would build something to operate on this freq.
Anyway, From looking at the foto.. I dont see a PLL sythesizer so you may just get away with just spreading the coil.
This in effect will change the operating freq.
Good luck with it...

[mikkojay]

Well, I gave it a shot, but the switch address changes did not resolve the conflict. The transmitter board has only: microprocessor, tin can oscillator, and buttons. I think I will use the 315 as the primary controller for single-player games, and use the 433 when I need a second controller. That's too bad, I really wish I would have known that before I ordered 2 of these without specifying different freq's for each.
Since these are 6 channel tx/rx, I was tempted just to leave them on the same freq and use 3 channels each, but I need at least 5 channels (or individual buttons) for the primary controller on more complex games-
hmm, I'll have to think about this one...
-Mike