I suck at this! resistoring soli mod what I do wrong?

voodoogreg · Aug 30, 2005

History:
I have been trying to learn more about FL's from modding solitaires. I went from the FLR.com 12v one to trying to setup a good light from a 3.7 (4.2 off chrgr) AAA li ion with a 26mcd 5mm. lesson 1) it's too much current, and need's a resistor. I use a couple of tables, go conservative with the ohm's (10)
wire it in the neg end spring. it was hinky so I soldered it and since I got two
li on's i test run both and the damn LED is dim as hell! (infact the non resistored one seem's almost normal)
What am I doing wrong!!!!!

any tip's would be appreciated! VDG

chimo · Aug 30, 2005

Start with a freshy charged batery.
Crank it up.
Measure the voltage drop across the resistor.
V=IxR (same as I=V/R)
You know V (from measuring) and you know R. Calculate I.
For these LEDs you do not want to go above 30mA if you value the long life of the LED.
If the calculated current is too small use a smaller resistor. If it is too high use a larger resistor.

If it is easy to replace the LED you may want to start with a higher current. Starting with a fresh battery will ensure the resistor is sized for the worst case situation for the LED.

Paul

voodoogreg · Aug 30, 2005

chimo said:
Start with a freshy charged batery.
Crank it up.
Measure the voltage drop across the resistor.
V=IxR (same as I=V/R)
You know V (from measuring) and you know R. Calculate I.
For these LEDs you do not want to go above 30mA if you value the long life of the LED.
If the calculated current is too small use a smaller resistor. If it is too high use a larger resistor.

If it is easy to replace the LED you may want to start with a higher current. Starting with a fresh battery will ensure the resistor is sized for the worst case situation for the LED.

Paul

Thanks paul, i pretty much did that. i even went a little conservative I wonder if it's placement. I stuck it in the bottom and soldered it to the spring and both side tab's. Man i am Po'ed. I can retube, bias, and do minor mod's ona tube guitar amp, but can even get a simple resistor to work!

chimo · Aug 30, 2005

Perhaps the resistor is getting shorted out and you are overdriving the LED. If a 5mm LED is seriously overdriven, it gets very dim. Do you have any pics?

voodoogreg · Aug 30, 2005

chimo said:
Perhaps the resistor is getting shorted out and you are overdriving the LED. If a 5mm LED is seriously overdriven, it gets very dim. Do you have any pics?

could e-mail them haven't got the posting picks thing down yet cool?

Could the resistor value raise the current? because I went with a safe value, and the other non-resistor identical soli is not dimmed anywhere near as bad? VDG

chimo · Aug 30, 2005

You will get "more eyes" on the problem if you post the pic.

Here is and easy and quick way to post a pic.
1. In a new browser window open: imageshack.us
2. Click the "Browse" button
3. Navigate to the location of your pic
4. DoubleClick on the pic you want to post
5. Click "Host It"
6. When the new window appears copy the contents of the second box (Thumbnails for Forums (1)) to the clipboard
7. Go back to your CPF post windo and paste what you just copied into your post.

This way you do not have to worry about the pic size as it appears as a thumbnail at CPF.

Here is an example:

voodoogreg · Aug 30, 2005

chimo said:
You will get "more eyes" on the problem if you post the pic.

Here is and easy and quick way to post a pic.
1. In a new browser window open: imageshack.us
2. Click the "Browse" button
3. Navigate to the location of your pic
4. DoubleClick on the pic you want to post
5. Click "Host It"
6. When the new window appears copy the contents of the second box (Thumbnails for Forums (1)) to the clipboard
7. Go back to your CPF post windo and paste what you just copied into your post.

This way you do not have to worry about the pic size as it appears as a thumbnail at CPF.

Here is an example:

coll, sound's easy I will do this later to day. what do you need to see? the resistor is kinda buried under the spring. should i unsolder it, and pull it out? VDG

greenLED · Aug 30, 2005

where on the spring did you solder it? You have to place it in such a way that one end of the resistor touches the (-) contact of the battery, and the other end touches the spring. If you soldered the resistor so that both ends of it are touching the spring, you won't get the same results.

... I think

voodoogreg · Aug 30, 2005

greenLED said:
where on the spring did you solder it? You have to place it in such a way that one end of the resistor touches the (-) contact of the battery, and the other end touches the spring. If you soldered the resistor so that both ends of it are touching the spring, you won't get the same results.

... I think

bingo, I soldered it cross ways on the clips, then the spring down on the clips, and whole shabang.
wrong? VDG

greenLED · Aug 30, 2005

By having the resistor soldered cross ways on the clips, it's not doing what it's supposed to. Solder one end of the resitor to the tip of the spring, and the other end to the bottom of the spring. Hopefully nothing will blow up (kidding!).

Someone with more electronics knowledge can probably explain better than me. The basic idea is that if you add a resistor in series (one after the other) in a circuit, the resistance is additive (200+100=300). If you add resistors in parallel, the resistance is additive but in 1/R form (1/200+1/300=....) so you're actually lowering the resistance of the circuit... Somebody else should explain this... help!

chimo · Aug 30, 2005

Sounds like you shorted out the resistor like I mentioned above. For this application, one end of the resistor must touch the neg terminal of the battery and the other end to the case. The spring is connected electrically to the clip and the case when it gets screwed on. The spring must not be allowed to touch the battery or the resistor leg that touches the battery. If it does, the resistor gets shunted and is bypassed by the shunt.

Is it really bright the instant you turn it on and then very quickly go dim?

chimo · Aug 30, 2005

greenLED said:
By having the resistor soldered cross ways on the clips, it's not doing what it's supposed to. Solder one end of the resitor to the tip of the spring, and the other end to the bottom of the spring. Hopefully nothing will blow up (kidding!).

Unfortunately this will not work either.

The spring will essentially short out the resistor. See my post above.

Paul

voodoogreg · Aug 30, 2005

greenLED said:
By having the resistor soldered cross ways on the clips, it's not doing what it's supposed to. Solder one end of the resitor to the tip of the spring, and the other end to the bottom of the spring. Hopefully nothing will blow up (kidding!).

Someone with more electronics knowledge can probably explain better than me. The basic idea is that if you add a resistor in series (one after the other) in a circuit, the resistance is additive (200+100=300). If you add resistors in parallel, the resistance is additive but in 1/R form (1/200+1/300=....) so you're actually lowering the resistance of the circuit... Somebody else should explain this... help!

Thnks that does make more sense. It also explains why it seemed to work wheni tested it out in differrent config'ss before just sticking it in and soldering away.VDG

voodoogreg · Aug 30, 2005

OK caught upwith the rapidfire replies, most appreciated! should i as a safty measure remove the whole assembly then put spring back, to avoid this shorting? you said solder on the spring then "case" meaning actual end plug? VDG

chimo · Aug 30, 2005

Here's a quick and dirty way to do it. The green material is an insulator.

greenLED · Aug 30, 2005

chimo's drawing is nice!

voodoogreg · Aug 30, 2005

Chimo thanks bro that I should be ableto do! thanks to G-LED too, I will report back. VDG

chimo · Aug 30, 2005

Good luck, and keep modding.....

voodoogreg · Aug 30, 2005

chimo said:
Here's a quick and dirty way to do it. The green material is an insulator.

One more question I promise, those wing's on the side are contacting the case right? so I can solder to it? the insolator is missing on mine but i got a few new one's in package's, and the bit seem's to help keep thing's straight. VDG

PS iwill keep modding, i just frustrate easy, and had got the front end tuned really well but then this all happened thanks again guys1

greenLED · Aug 30, 2005

voodoogreg said:
One more question I promise, those wing's on the side are contacting the case right? so I can solder to it?

I think so; they're the ones closing the circuit, IIRC.

I suck at this! resistoring soli mod what I do wrong?

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