I just got a barcode wand (Metal Pen) , unknown model
It has a DB9-Female , and if you take it apart there is 3 wires going to the PCB.
Black = DB9 Pin7
Red = DB9 Pin 2
Orange = DB9 Pin9
There was an Electrolytoc Cap (10uF 25v) , and from tracing the wires that one i could figure out that :
Black = Ground
Orange = +
Then Red must be Output i guess (i suppose TTL).
Well i hooked it up to +5v and connected my scope on the Red data pin and to ground , the scope is "quiet" when there is power on the pen (straight line on Zero volts) , there is a bit of noise when i remove power from the wand.
I got light in the pen , and did a swipe ...... Nothing happened on the scope.
Adjusted the scope to 500mv and 500ns , and got some reaction , but the level is absolutely not TTL , its maybe 50..100 mv.
There is a smd component marked Q1 on the PCB , it has same size as a BC850 (a BC547 SMD variant). Is the house called SO-23 it has got 3 legs , two in the bottom and ine in the middle on the opposite side.
The ligth pen part of the PCB is encapsulated in some kind of copper foil , and sealed. And out of that part comes a PCB trace that goes to a potmeter , and from that one it seems like it goes to Q1 , the left leg. Q1 the right leg goes to ground , and the leg in the middle goes to the Red wire (The output)
To me it looks like it is generating something on the scope , i get some small wawes (100mv or less, but it reacts when i swipe across some black and white text).
Q1 has the below marking 1AM and a symbol that looks like this >-|
1: Should i try with more than 5v ??
Could it be for +12v , and output RS-232 (i would prob not put my money on that one)
2: If Q1 is "dead" , does anyone know a replacement from the marking & symbol ???
Any hints are most welcome