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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Audronic on January 31, 2017, 12:57:18 AM
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Hi all
I have an Original Tank Mouse that has a faulty optical sensor .
Does any body know the Brand, model number of these Please.
Thanks Ray
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logically these should be in pairs. One IR emitter and One IR receiver.
Im not sure what brand / model, but you should do a keyword search like
rectangular LED infrared emitter and IR receiver diode
Examples
http://bit.ly/2kM9QIS
http://bit.ly/2joFg7x
You will need to check the circuit diagram to see if you need to replace the emitter or receiver. I think this is the schematic
http://pavouk.org/hw/en_amigamouse.html
Theres an upgrade to laser mouse for the original - http://amigastore.eu/en/559-laser-upgrade-for-amiga-mice.html
Edit - You might get better hits if you use the keyword 'phototransistor'
Example - http://bit.ly/2jx71Gj
Hard to find out what the original brand is. You will probably need to check datasheets and do some calculations based on the circuit given to check that the phototransistor is within spec. Or maybe just try one with a narrow beam like 30 degrees perhaps ?
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Hi darkage.
Thanks for all the info.
That really helps identify the receiver ( ? LDR ? Light Dependant Resistor ?).
The circuit is similar, but mine is an early one that came with an OLD 500.
Good to hear from somebody located in Victoria.
Thanks Again Ray
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Not quite. The receiver part is a diode, not a resistor.
So it goes on/off, depending if light is hitting it. Or whatever wavelength.
That's why you need a matching pair - so the correct wavelength gets sent out by the transmitter, and is received by the diode (receiver).
I don't think the originals are legal for sale anymore, brand new. They were not RoHS tested.
But, I guess a compatible pair is easy enough... one side is Light Emitting Diode (OK, might be infra red, not "light" technically.) The other side is Light Receiving diode (and has to match the LED, or close enough).
Other side is Receiving diode, so it only allows a current flow when the right wavelength is hitting it.
So long as they both work at +5V, and they physically fit in the holes and line up with the spinning disk, I guess it doesn't make much difference which matched pair you use.
Easiest probably to hack an old non-Amiga ball mouse for the parts. Should work OK. It's not like the Amiga pairs were special or terribly different, just the connector was wired different, where you plugged it into the computer.
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Not sure how old the mouse is (if the original tank mouse)
Heres an old diagram example - http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_mouse_repair/amiga_mouse_repair.html
Do both sides look the same? One should be a IR LED Diode (Emitter) and I would guess the other side is photo transistor (receiver) kind of like a LDR but different package but I would say they would use photo transistors as they are more senstive.
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Hi Pat,
The last schematic Ive posted clearly shows a phototransistor, for receiver
http://www.ianstedman.co.uk/Amiga/am...se_repair.html
The first schematic I posted, doesnt look like it has the correct symbols even for a photo diode. ie. no arrows on one set of diodes
Edit - You could just buy a pair to make sure its the same wavelength. It should be a NPN phototransistor for Rx, going by the last diagram. I assume slightly newer models should be the same before the new looking ones. It's not voltage that matters so much, its more about getting the one with the right current charactors as per the original ones.
https://www.sparkfun.com/products/241
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I know. But I never saw a transistor with two legs. Have you?
Here's a pic of a Logitech mouse PCB, from the same period. Two connectors on the components, two legs.
https://en.wikipedia.org/wiki/Computer_mouse#/media/File:Logitechms48.jpg
Anyway, that's the way I'd sort it. It's not exactly politically correct, but it should work.
Just replacing one side or the other, without knowing the operating wavelength, is asking for trouble. Replace the pair, it doesn't matter, you know they match.
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I know. But I never saw a transistor with two legs. Have you?
(http://learn.parallax.com/sites/default/files/content/shield/robo_ch6/phototrans.jpg)
A Transistor is basically a switch. Base is the light senstive material in lieu of a 3rd pin. The amount of light dictates how much current should pass between collector and emitter. Therefore just 2 pins.
Symbol is the same as in my last schematic.
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(shrug) Same difference. Both a two legged transistor and a diode are effectively wired the same, doing the same job. Neither will work if plugged in backwards.
Who cares so long as the buggers work? No, nevermind, I'm done here. I don't want yet another bashing.
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Not exactly the same. Photodiodes and phototransistors have different characteristics.
Phototransistor is more senstive than a Photodiode and is the symbol that is shown in the circuit diagram.
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@darkage, @Pat the Cat
Thanks for the info.
I am using Pavel's Circuit as a reference, The other one is totally different.
Included is a photo of the Old Tired Mouse.
Thanks Ray
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OK thats a Tank mouse with a LM339 ic.
Heres a very good discussion that covers same topics.
http://www.atari-forum.com/viewtopic.php?t=20207#p177259
Someone else on that discussion has picked up that the first diagram is wrong with the strange double diode symbol as well. They also suggest phototransistor is a more appropriate setup
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Thanks @darkage, Pat the Cat
Thats where i started some days ago.
Thanks Ray
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Official name is 'Phototransistor side looker (looking) package'
I would measure exact package dimensions plus pin width (measured from center pin to center pin) with a digital caliper and then try to match one up with same physical dimensions and supports IR.
List of phototransistor side looking package -
Rs Components (free shipping - no minimum order amount) http://bit.ly/2kOG95B
Element14 - http://bit.ly/2klZTRl
Ordering from Rs Components is cheap, probably worth to get at least 2 different brands to try. maybe honeywell or osram. Check acceptable angle, it should be something sensible and not too wide. Maybe 50 degrees or lower
Edit - You will probably need to get a matching pair, so grab a IR LED (emitter) side looking package as well. Same brand / operating specs.
Note - Only if your certain that the fault is with the optical sensor. There could be issues on other parts of the board / cable.
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Hi @darkage and @Pat the Cat.
Problem Sorted ?
The load on the IR Reciever was to low (Original Design) which was 670 Ohms.
Now modified to 2.7K ohms as per Pavel Ruzicka's Circuit.
I have changed all 5 Resistors to this standard.
Thanks for all your help.
Ray
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Problem Sorted ?
The load on the IR Reciever was to low (Original Design) which was 670 Ohms.
Now modified to 2.7K ohms as per Pavel Ruzicka's Circuit.
I have changed all 5 Resistors to this standard.
Thanks for all your help.
Ray
Odd. Was the board worked on before ? Im not sure if Pavel's schematic would be 100% correct, best way would be to check another untouched tank mouse for values. Or maybe your mouse was built on a friday afternoon in the factory and someone put in the wrong values. Or maybe overtime as the optical sensor ages it might become less senstive and a load change has done some magic.
Happy its working now :P
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@darkage
It looks like the 3 that I had problems with, were all with the low value resistors ??
Pavel's Circuit did not match the Old Tank Mouse, But i used it as an example of how a mouse could be wired.
Thanks Ray
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A larger resistive load will make it more sensitive.
Theory here, key point towards the end.
http://learn.parallax.com/tutorials/robot/shield-bot/robotics-board-education-shield-arduino/chapter-6-light-sensitive-11
If its the original resistors in there from the factory, the phototransistor may be breakingdown with age and is drifting out of spec ? See how you go, if it happens again then look at the sensors.
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@darkage
Ok Thanks for the journey down the Ohms law road I haven't reviewed that for a lot of years.
Ps :- I am an Old techo, and i still like some of these challenges.
Thanks again
Ray
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Hi @darkage and @Pat the Cat.
Problem Sorted ?
The load on the IR Reciever was to low (Original Design) which was 670 Ohms.
Now modified to 2.7K ohms as per Pavel Ruzicka's Circuit.
I have changed all 5 Resistors to this standard.
Thanks for all your help.
Ray
Fix is a fix. :drink:
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@Pat the Cat
Thanks for your help.
All sorted (At the Moment)
Thanks Ray