Re: simple high/low drop-in for Arc LS / L4
Hi Folks,
I'm going to try to describe the new version and the technique used to build it.
General:
A single spring is insulated from a brass washer. A resistor is connected from the washer to the spring, as low as possible. The resistor is bent in such a way that as the spring is compressed the lowest loop contacts the resistor's lead, giving full power.
There are several key points;
<ul type="square">[*] Soldering should be done before applying epoxy. Heat weakens epoxy.
[*] The resistor's leads should not have to move. If they do, they will eventually break.
[*] The lowest coil should be coated with epoxy to prevent the contact from shorting.
[*] A 1/4 watt resistor can be made to fit. These are easier to find than 1/8 watt.
[*] The epoxy sets quickly, so only epoxy 3 or 4 at a time. I find that I make 3 batches of epoxy with each run. One to paste the spacers, one to attach the spring and a final to make sure the bottom coil and resistor are properly coated.
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PARTS LIST:
Spring - 3/8 x 3/4 x .032 (C-566 from century springs). Use one half
Resistor - 10 ohms for an LSH-P
Washer - Brass #6 from True Value. 3/8th inch outside diameter.
Spacer - Cardboard or plastic disc cut to match washer.
Here's the spacer, the resistor soldered to the washer and the spring.
Supplies:
JB-Weld - Kwik or Marine.
Solder - 40/60 rosin core
Tools:
Low wattage soldering iron with small tip
Needle nose pliers
Fine sand paper (200 grit or finer)
Small file or dremel with grinder.
Exacto knife or scalpel.
Any ohm-meter (DMM, analog, etc).
Pictures:
In these drawings, the gold is the brass washer. The light grey is the plastic spacer. The dark grey are the leads. The spring is blue and the brown is the resistor.
This is a drawing of the device from above. Note the lead of the resistor that goes all the way to the edge and then folds back on itself before connecting to the washer. The spacer is not shown for clarity.
This next drawing is a cutaway from the side. It gives an idea of the layers involved.
Next we have the side view.
Ok, here's the project without the final epoxy coat. The spacer is epoxied to the washer. In the second you can see the edge of the resistor's lead pushed out of the way so that it doesn't get epoxy on it in the next step.
And lastly, the finished product. In the second picture the contact is clearly visible.
Adjustments:
Like the type 1 spring assembly, the springs should be short enough that no extra pressure is placed on the battery when fully compressed. There are enough variations in the battery pack, battery size and kroll switch that no single spring length will be perfect. Follow the spring length instructions from the type 1 instructions.
After the spring is short enough, you can adjust the contact point by bending the top coil of the spring down or up. Use two pairs of pliers to avoid over stressing the epoxy. Bend the last coil towards the washer to delay the full beam. Bend it up (away from the washer) to cause the full beam when the battery pack is only half screwed in.
No, I am not selling these.
Daniel