Ok these instructions are written for people with hardly any electronic experience so anyone can make this circuit using a simple grid guide.
View attachment 57711
Here is the component list
1 x project strip board (any size but I cut mine down to the size in the diagram)
2 x 5mm LEDs (diffused not clear)
2 x 470 ohm Resistors
2 x 22K ohm Resistors
2 x 2N2222 NPN Transistors
2 x 47uF (10v or 25v) capacitors (you can increase/decrease this value and it will slow down/speed up the flashing)
Also needed:-
1 x AA battery holder
2 x AA batteries
some bits of wire
and obvious tools like a soldering iron, solder, wire cutters etc etc
For all you novices out there, you can solder in the resistors in any direction ie they are not polarity specific, where as the other components must be put in the correct way round or it will not work or you will have odd results!
Ok lets get started.. (after step 1 there is no particular order, I just did it this way to make it easier to write)
1. Prepare the strip board.
With the copper strips facing you and running left to right you need to break the copper tracks in 2 positions, just use a hobby knife to do this. You need to break the track between E8 - F8 and then F7-G7. Now flip it over so the copper tracks are at the bottom as you'll be putting the components on the blank side and soldering from underneath.
2. Resistors.
Resistors are not polarity dependent so you can solder these easily, just make sure you solder them in the right places.
the 470ohm resistors need to be soldered between these points: E4-E7 and I3-I7
the 22Kohm resistors need to be soldered between these points: C1-C8 and K1-K8
(hint.. when you cut the excess length of leg from the 470ohm resistors keep the off cuts as we'll use this to make 2 track bridges)
3. The capacitors.
These need to be soldered the right way round. If you look on the capacitor body one of the sides will be marked in some what which will denote its negative leg which should also be the shorter leg, bare this in mind when soldering them in.
the first Capacitor needs to be soldered between F6-F7 where F6 is where the negative leg must be.
the second Capacitor needs to be soldered between H5-H7 where H5 is where the negative leg must be.
4. The Transistors.
As before these have to soldered/positioned in a particular way, if you look at the diagram the 2N2222 NPN Transistor it has a flat face which must be facing to the left which puts the Emmitter leg on row 9, dont worry if you dont know what that means, just look at the diagram.
Transistor 1 is soldered in D7-D8-D9
Transistor 2 is soldered in J7-J8-J9
5. Bridging Tracks.
Use an off cut from the resistor legs to bridge B5-B8 and then another to bridge G6-G8
6. The LED's
LED's are basically diodes so these also need to be soldered in particular way. If you look at the bottom of the LED body you'll see that the flange has a flat spot, the leg closest to that is the negative and if you follow it up to the inside of the LED it ends in larger shape inside the plastic case. the longer leg is the positive.
You can solder the LEDs anywhere along the board as long as the positive and negatives follow the tracks I list below, so you can adjust the fit for holes in your Rangefinder or just connect the LED's via some wire.. the choice is yours.
LED #1 Positive leg anywhere along track 1, negative on track 4
LED #2 Positive leg anywhere along track 1, negative on track 3
7. Power
Now all you need to do is connect the battery pack positive to track 1 and negative to track 9 and your LED's should flash. This circuit should operate fine from 3v to 9v but I like running things low so I run mine at 3v.
8. Optional
You can add a clear LED for the viewfinder to the circuit, just put another 470ohm resistor between the positve track (track 1) and the positive leg of the LED and then solder the negative leg to anwhere on track 9.. this will obviously not flash.
