Ti-83 plus wireless link circuit help - Page 3 - Electronic Circuits Projects Diagrams Free

**Nigel Goodwin** · 29th March 2006, 07:01 AM

Quote:

Originally Posted by DigiTan

Why won't anybody help me? :cry:

Why don't you build it and try it?.

DigiTan · 29th March 2006, 10:01 PM

I'm having a lot of grade trouble in my EE major, so I don't get to build much anymore. Actually, I've been thinking of giving up on my degree. :cry: There aren't a lot of parts though, so I guess I could do it as long as I can get the coils right. When it says the coils are [.27-.3], that's in millihenrys right?

arigold125 · 30th March 2006, 07:41 PM

How would i use a pic and a transmitter chip from LINX??
is that the easiest way to do this?? I,unlike digitan, am most intrested in building the simplest, cheapest wireless transmitter possible. I only need it to go a couple of feet and allow me to send files back and forth with a pair of TI calculators.

30th March 2006, 08:22 PM

hi arigold
Try looking at www.rentron.com for some good ideas.

arigold125 · 30th March 2006, 08:37 PM

ok but i dont have much experience doing this sort of stuff, so i really need something that is fully planned out

DigiTan · 31st March 2006, 11:19 PM

Quote:

Originally Posted by arigold125

How would i use a pic and a transmitter chip from LINX??
is that the easiest way to do this?? I,unlike digitan, am most intrested in building the simplest, cheapest wireless transmitter possible.

LINX mods only support a data rate of ~5000bps, which is only about half the minimum rate used by TI-OS--or 1/4 if it's a 68k model. That limit's compounded by the fact that you're encoding for 2 bi-directional lines instead of one, and since TI-OS and all third party software use the DBUS protocol, you need to encode both lines at all times to support handshaking. That's a lot of encoding to do at only 4800bps.

The posted schematic might not have that problem, but since it doesn't amplify the recieved signal, I doubt it can sink enough current for the TI calc to read. I was hoping Nigel, audio or the others could recommend something; but so far I've gotten more questions than answers.

mramos1 · 2nd April 2006, 04:47 PM

Quote:

Originally Posted by arigold125

How would i use a pic and a transmitter chip from LINX??
is that the easiest way to do this?? I,unlike digitan, am most intrested in building the simplest, cheapest wireless transmitter possible. I only need it to go a couple of feet and allow me to send files back and forth with a pair of TI calculators.

You are not cheating are you? Or helping someone in class? Send data between calculators...

Someone mentioned radiotronics parts in another topic, they were low cost ($4 each I think they said), you can make your own antenna (rather than buy one). Maybe hit the radiotronix website and see what they have.

Is the output from the TI RS232 TTL levels? I will have to go back and read the posts again.

DigiTan · 5th April 2006, 04:10 AM

The outputs and input for TIs are at TTL levels, and each use 1 bipolar transistor for logic switching. For inputs, they use diodes and pull up resistors to read the current state of the lines. The more detailed description is on Ticalc's Technical Information Archive titled "All about the 86 Link Port." (I couldn't direct-link).

Anyway, the diodes are why I wanted to ask audio and Nigel about the reciever. I'm pretty sure a crystal radio couldn't draw enough current through the diodes to switch the inputs from high (idle) to low. But if no one wants to help, I say screw 'em all; maybe some CW transeiver circuits would do the job. It's just a real pain encoding for 2 bi-directional lines at once. It would have to be done without a duplexer as well.

**Nigel Goodwin** · 5th April 2006, 08:04 AM

Quote:

Originally Posted by DigiTan

Anyway, the diodes are why I wanted to ask audio and Nigel about the reciever. I'm pretty sure a crystal radio couldn't draw enough current through the diodes to switch the inputs from high (idle) to low.

I don't see why not?, a CMOS input requires almost no current at all - I'm just dubious about a crystal receiver working at all?.

Basically, as I said before, you need to build it and try - no good asking here, as no one has built it.

arigold125 · 6th April 2006, 03:32 AM

I finally found this-
http://renaud.cerrato.free.fr/old/PIC92.htm

I'd rather not have to build it though. If anyone is willing to build it for me please email me with a price quote of how much over the cost of the parts you would be willing to build it for. Schmidtzen (att) Gmail(dot) com

DigiTan · 6th April 2006, 04:29 AM

That's pretty cool. I was suspecting using the same frequency for transmission and receiving would cause collision problems.

Quote:

Originally Posted by Nigel Goodwin

I don't see why not?, a CMOS input requires almost no current at all - I'm just dubious about a crystal receiver working at all?.

Basically, as I said before, you need to build it and try - no good asking here, as no one has built it.

Yeah, I see what you mean. For the inputs they were using SI diodes instead of a CMOS amp, which was conserning me about the voltage drop. I guess I'll look into this one over the summer.

13th April 2006, 01:28 AM

LINX's newer LR series can handle data rates up to 10000bps.

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29th March 2006, 10:01 PM	(permalink)
DigiTan	I'm having a lot of grade trouble in my EE major, so I don't get to build much anymore. Actually, I've been thinking of giving up on my degree. :cry: There aren't a lot of parts though, so I guess I could do it as long as I can get the coils right. When it says the coils are [.27-.3], that's in millihenrys right? __________________ The most-hated young engineer in America. * AVR Projects * Robot War: TI * About

30th March 2006, 07:41 PM	(permalink)
arigold125	wireless How would i use a pic and a transmitter chip from LINX?? is that the easiest way to do this?? I,unlike digitan, am most intrested in building the simplest, cheapest wireless transmitter possible. I only need it to go a couple of feet and allow me to send files back and forth with a pair of TI calculators.

30th March 2006, 08:22 PM	(permalink)
hyedenny	hi arigold Try looking at www.rentron.com for some good ideas.

30th March 2006, 08:37 PM	(permalink)
arigold125	wireless ok but i dont have much experience doing this sort of stuff, so i really need something that is fully planned out

5th April 2006, 04:10 AM	(permalink)
DigiTan	The outputs and input for TIs are at TTL levels, and each use 1 bipolar transistor for logic switching. For inputs, they use diodes and pull up resistors to read the current state of the lines. The more detailed description is on Ticalc's Technical Information Archive titled "All about the 86 Link Port." (I couldn't direct-link). Anyway, the diodes are why I wanted to ask audio and Nigel about the reciever. I'm pretty sure a crystal radio couldn't draw enough current through the diodes to switch the inputs from high (idle) to low. But if no one wants to help, I say screw 'em all; maybe some CW transeiver circuits would do the job. It's just a real pain encoding for 2 bi-directional lines at once. It would have to be done without a duplexer as well. __________________ The most-hated young engineer in America. * AVR Projects * Robot War: TI * About

6th April 2006, 03:32 AM	(permalink)
arigold125	TI wireless I finally found this- http://renaud.cerrato.free.fr/old/PIC92.htm I'd rather not have to build it though. If anyone is willing to build it for me please email me with a price quote of how much over the cost of the parts you would be willing to build it for. Schmidtzen (att) Gmail(dot) com

13th April 2006, 01:28 AM	(permalink)
hyedenny	LINX's newer LR series can handle data rates up to 10000bps.