wireless multimeter/display

[gilligan1]

I am looking to build a wireless display for a multimeter i do alot of work where it takes two people to do stuff becouse the meter is in a place that i cannot see it and the adjusting is in another place. It would need to transmit to the reciever that at the most will be 500 ft away but would like it to be able to do 1000 ft All the reciever unit would have to be is something like a digital clock display (led display?) I would like to be able to modify my multimeter i have now gb instruments gdt-294a so i could just plug the transmitter into it. Or if all else fails to make it alot simpler just 0-10.00 volts is the range most of our work is done in.

 

[checkmate]

I would not be surprised if the transmitter/receiver circuit alone costs a couple of DMMs.

 

[gilligan1]

that would be fine with me but i don't really understand how to link the two of them or link one to a remote display i know i need a transmitter and a reciever. and possibly some coding and decoding

 

[checkmate]

There are a lot of transmitter and receiver chips that handle the encoding/decoding parts for you, and they don't come cheap. For display, you can just use a PIC interfaced to a LCD display. But all these are just the easy parts.

The most difficult part is how to interface the DMM itself, which may be close to impossible. It would probably be easier to build one from scratch.

 

[gilligan1]

by the way it sounds if i make a volt meter since most of my work is between 0-10.00 volts send the reading to a transmitter to the reciever to the pic to the lcd screen. A voltage to frequency converter between the transmitter and the meter? or would the encoding and decoding take care of this for me in the transmitter and reciever. this is my first project i've done in the last 6 yrs so some things are still a little foggy to me.

 

[gilligan1]

a friend suggested using a frequency counter becouse the refresh rate would be better but i was wondering what other thoughts where on it

 

[Nigel Goodwin]

a friend suggested using a frequency counter becouse the refresh rate would be better but i was wondering what other thoughts where on it

I don't see why?, it seems a fairly bizarre idea!.

As you're making the unit yourself, the refresh rate is anything you want it to be - I don't really see why a fast refresh rate is important?, you can't see the digits changing if they are too fast.

Use a PIC with an A2D converter to measure the voltage, connect that to a licence free radio transmitter module that has sufficient range - it will need to be a fairly expensive one, as you have a long range requirement.

At the receiver, connect the radio receiver module to a PIC, and connect that to an LCD text display module.

You can buy radio modules which have inbuilt encoders and decoders, these simply accept RS232 serial signals, these would simplify your project, rather than having to write your own radio protocol.

 

[Oznog]

You want to do something cool, build a wireless DMM into a pair of heads-up display glasses. THAT would kick ass. You'd always be able to use both hands, focus straight on your work, and see the digits floating in front of you.

 

[gilligan1]

thanks for the help that really makes sense to do it the way. I prolly won't have it built until end of january(due to r/c helicoptor purchase). I'm allways open to other ideas on this subject I like the heads up dispay if i can find a pair of glasses with it i would probably do it so i could interchange between the glasses and an lcd display. the only problem i see is in the winter months up here trying to keep the display from freezing nothing a couple of handwarmers won't take care of tho. lol

 

[evandude]

a lot of DMMs have RS232 serial interfaces; you could find or build a transmitter for serial data very easily I'm sure, and then on the other end, decoding wouldn't be very hard either.

 

[gilligan1]

getting a multimeter with the rs232 is a good idea for me anyways i'm going to do some reasearch on that most of the transmitters i have be looking at support it. Of course it's a standard for what i can tell in communication. I found a schematic for nigel's idea that would take a few small modifications whats your thoughts on it? I might be able to get parts sooner than expected i thought pics where more expensive. need to get a programmer for it tho but would be nice to have for future projects anyways. Thanks for all the help guys i really appreciate it. here is the link for that schematic http://lea.hamradio.si/~s57nan/ham_radio/fc_led_2/fcl2_sch.gif