Resistor Precision

How to aim a laser beam on a photoresistor 40m away?

I need to direct a laser beam from a cheap laser pointer to a photoresistor 40m away. The area of the resistor is less than 1 sq. cm., so the pointer needs to be aligned precisely. I tried fixing the pointer on a camera tripod but I need more precision. Any ideas on how to do this?
The problem is aiming correctly.

I once had a telescope that had an alignment ring for the viewfinder. This was a ring with 3 screws around it and the viewfinder in the middle. You could use a screwdriver to turn each of the screws and thus aim easily by moving the viewfinder in very fine steps.

I was thinking that maybe something like that existed for this particular application, that I could find easily.
Although a theodolite would be perfect, it's way out of my project's budget...any other ideas?

One could make a fairly precise aiming device from two strap hinges, 2 springs (moderately stiff) , 2 machine screws (preferably fairly fine thread) and 2 wing or knurled nuts. Placing the spring between the two leaves of the spring with the screw holding it together give one a fine angle adjustment, connecting two at right angles can give one altitude and azimuth adjustment. Attach your pointer to the assembly, and the assembly to a sturdy support (perhaps you tripod with some ballast, maybe a jug of water or a sandbag)

EDIT;
As an example, supposing one got hinges that were 10cm between the hinge pin and the hole the bolt goes through, further the bolt has a thread pitch of 0.5mm , in this case, about a 20° turn of the adjusting nut will make a one minute of arc change in the angle of the hinge, I would guess that with a moderately stiff spring to remove slack from the mechanism, a light touch on the screw and a very sturdy support, a couple arc seconds adjustment might be possible
One might also _try_ a lens to diverge the beam a bit, while this will reduce the light falling on the photo resistor, it might still be enough and could make aiming easier.

Five Band Resistor Color Code - What Does The Last Band Of White Color Represent?

In electronic repair, most of the time I came across five band resistor color code. The purpose of using the five color band resistor in a circuit is that it will provide a more accurate value compare to the four color band. For example in order to get the value of 22.6kohm, with four colors band resistor you will not be able to find it. The most you can get is 22k (red, red, orange and gold). If with the five color band you will be able to calculate it (red, red, blue, red, brown)the last color which is brown represent 1% tolerance. You may go to google search engine and type resistor color code, resistor color coding, resistor color code calculator, or resistor color code chart to know more about how to calculate a five band resistor values.

If you open up an analog multimeter you will understand what I mean. Most of the resistors circuit inside the multimeter are using five color band. Why? Because the reading that you get whenever you measure current, voltage or ohm, the panel will show the nearest value. For instance, if you measure a 9v battery the needle will point to may be 8.9v, 9v, or 9.1 volt. If that particular multimeter was designed using four color band resistor the result that it gets may be 8.5v, 9.5v or even 10 volt. In other words the use of five color band resistor is to make a circuit more precise and output the desire result as what the engineers want it to be.

There was a interesting five color band resistor which was very unique. In fact i have already seen quite a number of them. I will reveal the calculation about this unique five color band resistor. The colors are orange, orange, red, gold, white. Actually it is a four color band resistor. Just ignore the white color and proceed to calculate using the four color band formula. As to why the resistor manufacturers add this 'extra' white band i really do not know. However, from forum someone said that it is for the military purposes. If you know the answer i would like you to email me so that I can share with other fellow electronic repairer through this info repairing newsletter.

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Electrical & Test Equipment » precision_resistor

Resistor Precision

Five Band Resistor Color Code - What Does The Last Band Of White Color Represent?