IF for JR Quattro Lite - Someone Help Please!!!!!!

[Andy J]

I have built the curcuit on

and can not get it to work. Tried it on two different computers so I don't think it is the computer. Can someone give me some pointers to trouble shoot the curcuit?
I saw a post from someone who had a JR Jline Quattro that tried this IF and said it worked great. I think my Tx is the same. I think its just called Lite 'cuz it came with micro servos.
I have checked and rechecked and rechecked my curcuit many times. This last time I rebuilt it I even put a label over the board and drew the scematic on it then put the components on the symbols to make sure I had them all connected corectly.

How can I find whats wrong? Help Please..........

[Andy J]

Curcuit on this website

oops

[Andy J]

Here is what my IF looks like.

I am only showing 1.2v AC on pin 9 (signal into computer?) in respect to ground.
Here is what I am reading on my meter across the resistors.

No Tx w/ Tx
AC DC AC DC
R1 0 7.8 0 7.6
R2 0 8.2 0.4 7.9
R3 0 0 0 0.025
R4 0 0 0 0.1
R5 0 4.3 1 5.2
R6 0 0 0 0.05

Anyone with a working version of this that could tell me the readings I should be getting?

[Steve Lewin]

Even though I drew that circuit I'm embarassed to tell you that I don't have one myself at the moment. I'm using the newer PIC circuit now and have sold/given away all my old serial interfaces. The voltages look fairly sensible but I'll throw a circuit together and give you a more definite answer as soon as I can.

Unless anyone else can help ?

Steve

[Mike Roberts]

Andy

A quick check - which Windows system are you using?

Did you have FMS running when you checked the voltages (affects voltages from serial port)?

What is voltage across Q1 for each case?

Mike

[Andy J]

I am using windows 98SE

I had FMS running with the interface calibration screen on.
I have the +8v on pins 1,6,& 7 and -8v on pins 4 & 9. ???

voltages for Q1 Base to Collector are

no Tx w/ Tx
AC DC AC DC
0 11 1 10

Mike,

I had built your interface first but I had pins 7 and 9 switched. When I realized it I switched them to back, but after I switched them back, I checked the transistors to see if I had them right and thought I had put PNP for NPN and vise versa so I changed all the transistors. It did not work after that so I tried to make a combo of your curciut and steve's by adding another amp stage at the beginning. Then I found out that when I check diodes on my meter, (just a cheap analoge from my ITT Tech days) the negative lead has to be on the anode and the positive on the cathode to forward bias it(backwards of a good meter). So now I realise that I had the transistors in correctly to start with, but the curcuit board is very messed up with all the changes I made. So I built Steve's curcuit on a second board. I think I'll try to fix the first one all up tomarrow. One of them should work.



My Tx has a signal from the trainer cord but I can't measure it with my meter. I hear it when I plug on of my PC speakers into it though.....
The JR Tx is only a month old and only used once( I bought a GWS zero and crashed it first time out :0 ). I would like to use my Tx to get some practice untill I can fix my zero( found a plane that is just like it for FMS). Not as easy to fly as I was lead to belive from the LHS. I need to get a trainer when I get some cash.

[Andy J]

???
Seems to me I don't have enough signal coming in.
Have a digital auto ranging multimeter from Radio Shack now.
Voltages are about the same, but now I can read the AC in and it is only about 200mV AC.
It is a signal...
I saw it on winscope.
A freeware software O-scope (unable to check amplitude with it though) just before I burned out my microphone input on my soundcard. It was built into my mother board. Its OK though becuse I have a better sound card that I was meaning to put in anyway.
Anyone know of a simple curcuit I could make that could bring signals down to a 'safe' level for a microphone input and also would be easily read as to how much the signal is being attenuated so I could use this software and know amplitude?

I've built both curcuits now, and niether one can give me enough gain to get FMS to see the signal.
They seem to be working fine in both counts but the output signals are only a little over 1V AC on both. Is my Tx messed up? And if so does anyone know how to fix it or where I could get a scematic for it?

[Andy J]

OK now I am thoughly confused.
I just got back from the Hobby Shop. I checked another JR Quttro output on the buddy cable and it read 238 mV AC also. So, I guess my Tx is OK after all.
I also checked a JR XP662. It ouptuts 300mV AC. It seems this model Tx has much less output signal on the buddy cable than the other JR radios. Can someone modify an interface so I can get enough gain for FMS? Do you think I might get enough gain if I add a .01uF cap across R5? (I think I'll try it. Couldn't hurt, I don't think...)

[Andy J]

I can't get anything to work. I've tried both curcuits.
I have them on breadboards now so I can test easier.
The R5 test, that is sapossed to go from 13v down to 8v when I plug in my Tx does not happen. It seems like I loose alot of my signal from the collector of Q1 to the base of Q2 on the two transisor version. ???
Did everyone give up on me?

[Steve Lewin]

It's not the output voltage, I've just measured the JR Max 6 that works perfectly with my circuit and it shows 210 mV.

I guess we're all running out of things to suggest. If you've tried both circuits, you're confident the transistors are o.k., right types, right way round, there's not very much else that can go wrong.

Ignoring the technical details for a moment you never have said exactly what symptoms you get when you try to calibrate in FMS. Do you see no signal at all ? Same with both circuits ? Does the serial port you're using work with anything else ?

Steve

[Steve Lewin]

I don't know, you try to help and people just ignore you ;(

Steve

[Andy J]

Sorry I didn't get back to you.
I've been searching for a way to amplify my amperage on the out put of my remote. (I think I burned something out inside it. ) It has the correct voltage but when I connect it to my comp with the curcuit it doesn't get enough current to the curcuit.(I think) The reason I think this is I put the signal through an old tape recorder and the curcuit runs at the specifications, even with the volume tuned down so I read only 230mV on the input to the curcuit, but I think there is way to much noise being introduced because FMS still doesn't respond(not even a twitch on the controle gages. I don't think it is worth sending it to horrizon hobby just for that since it still works fine with my model.
It looks like a common collector amp is in order but I can't figure anything out that works. I know how to calculate all the gain and voltages in curcuits but I was not tought how to engineer them. I've been trying lots of different configurations. But what looks good on paper never seems to work in the real world so far. Any suggestions would be greatly apreciated. Again sory for not checking back here sooner. I am about ready to just order a buddy JR remote I've seen them advertised for $35.

[Steve Lewin]

As I say my Max6 only reads 210mV so it's not that. The current required by either of the circuits is tiny so it's not likely to be that either.

Exactly what transistors are you using and are you certain they're the right way round ? There's so little to go wrong with these circuits that it's difficult to imagine what else can be wrong unless your COM port simply doesn't work.

I don't understand what you're saying about the tape recorder. If there was too much noise you would get lots of movement in the calibration screen not none. Also if the circuit was running to specification you would see the bars moving.

If you have a soundcard why not try the soundcard oscilloscope that "Coolbean" was using then we can see exactly what's going on in your circuit. See threads "Please help" and "waveform" below for details.

Steve