Dorcy 1AAA 1LED circuit data

I am almost certain that I have seen a post that discussed non-destructive disassembly of the Dorcy 1AAA. I have searched for it but cannot find it. Can someone point me to the right thread. Thanks to CPF member jcciv, I now have one in my possession. I would like to disassemble it and measure the efficiency of its convertor. TIA.

Re: Dorcy 1AAA 1LED disassembly. Help!

I can't find it either, but remember some of what was said.

You can use a butter knife in the slots, or a strap wrench on the head.

Re: Dorcy 1AAA 1LED disassembly. Help!

or you can summon all the strength in your upper body!

Re: Dorcy 1AAA 1LED disassembly. Help!

2 channelocks/vicegrips, carefully applied. it is standard thread (righty-tighty).

use the longest wrenches you have, and if you are careful, you can break the loktite or whatever is holding them together. it is surprisingly strong. you still might ding tha metal a bit.

i thought about adding a little heat--if you are gentle, the heat may help to break the bond, without harming the light.

Bob

Re: Dorcy 1AAA 1LED disassembly. Help!

[ QUOTE ]
TheBeam said:
I can't find it either, but remember some of what was said.

You can use a butter knife in the slots, or a strap wrench on the head.

[/ QUOTE ]

The strap wrench gave me a headache and made my eyes bug out. /ubbthreads/images/graemlins/tongue.gif

Thanks to everyone for the tips.

Re: Dorcy 1AAA 1LED disassembly. Help!

My family has three. One of the heads was easy to unscrew with out even a grunt ( I don't mean a Marine /ubbthreads/images/graemlins/smile.gif )

Re: Dorcy 1AAA 1LED disassembly. Help!

Here is the thread for the Dorcy 1AAA Review.
In it, there are descriptions and pictures of the LED light
disassy'd. I had no problem removing the head assy. Guess
there was not that much threadlock/Loktite on mine.

Good luck! Neat lil lite! [my EDC]

Danno

Re: Dorcy 1AAA 1LED disassembly. Help!

Thanks guys for the help. I have it apart. I have reverse engineered the circuit and used a scope to check the waveforms at all the nodes. Here is the kicker, this seemingly simple circuit [6 components, effectively only 5 since two are in parallel] has me baffled. It does not appear that it should work but it does. /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif
If anyone else reverse engineers this circuit, please explain it to me. I am highly embarrassed.

Re: Dorcy 1AAA 1LED disassembly. Help!

If you do figure out its function, Please share it with me.

The circuit seems to work very well. I drained a aaa battery in the solitare till it went dark, moved the battery over to my arc aaa standard and ran it for several hours. By this time the arc was getting pretty dim. I turned off the arc and tried to restart it. It wouldn't fire back up. I then tried the battery in the sonic, nothing. The Dorcy fired right up on the battery. It was dim, but usable. Tried the arc again, nothing.

Its a shame these are so hard to find. They would be great to play with. Anyone attempted to run one from 3 volts yet?

Dorcy 1AAA 1LED Circuit efficiency test data

[ QUOTE ]
TCG said:
If you do figure out its function, Please share it with me.



[/ QUOTE ]

I now have some data on how *well* it works. I took some efficiency data while powering from a variable bench supply. Yes, it can sure suck a battery dry. My supply goes down to 0.22V and the circuit was still operating at that voltage delivering 0.7mA to the LED. The circuit requires a minimum Vin of .65V to startup. Here is the data:

<font class="small">Code:</font><hr /><pre>
Vin Iout[mA] Eff[%]
.50 4.3 66.5
.70 8.4 66.8
.90 15.2 69.4
1.1 23.4 70.6
1.2 34.4 72.4
1.3 53.0 70.5
1.5 95.6 67.7

LED Vf ranged from 3.089V at 4.3mA to 3.816 at 95.6mA.
</pre><hr />

For the vast majority of discharge of an AAA cell, the voltage will be in the range of 0.9 to 1.3V. The efficiencies around 70% are really quite good for such a simple circuit operating at such low input voltages. The oscillation frequency ranged from 161.2 kHz at Vin=0.50 to 128.8 kHz at Vin=1.5V.
Now that I have studied the circuit a bit more, I believe that some modders may want to use this board for other applications. I think that this board has potential for some hotrodding. I will post further once I have played with it more. As is, I think this light is a candidate for a very cheap 1AAA Luxeon conversion. It should deliver around 45mA into a low Vf 1W luxeon from a NiMh cell. 1W white luxeons reach their peak efficiencies in the range of 40-80mA drive current.

EDIT: This post has been extentively revised. Original data was incorrect due to test setup error.

Re: Dorcy 1AAA 1LED Circuit efficiency test data

Thanks for the data. A polynomial curve fit of the current gets pretty scarry by 3 volts.

Let me be sure I understand it thou.

Iout is the measured current to the led?

Iin = Iout*Vf/Vin/eff?

interesting data. Thanks for sharing.

Re: Dorcy 1AAA 1LED Circuit efficiency test data

[ QUOTE ]
TCG said:
Let me be sure I understand it thou.

Iout is the measured current to the led?

Iin = Iout*Vf/Vin/eff?



[/ QUOTE ]

Yes to both.

Re: Dorcy 1AAA 1LED Circuit efficiency test data

Just what is the circut (in very general terms)? How does it compare to the "joule thief" (the same? different concept?)...

I'm guessing one of the components is a transformer (sort of a tiny flyback).

Re: Dorcy 1AAA 1LED Circuit efficiency test data

Hi Doug S.

Just now picked up on this thread (actually I've been away from CPF for a while - unsuccessful attempt to shake a flashlight addiction).

First, I'm surprised you haven't been able to find the Dorcy 1AAA in Nashville. I live in North Alabama, and our Wal Marts here don't have them, but last week I was in Lebanon, TN, and picked up on in the Wal Mart there. After using the light I now wish I had bought all they had.

I am so impressed with this little light that now I REALLY want the 1AA/3LED light. I have been unable to find one anywhere, but I contacted Dorcy and sweet talked a sales rep into letting me buy direct in quantity. After she talked with her manager, she agreed to sell them to me for $10.00 each plus shipping. On the surface it appears that I can get them to my hous for 10-12 dollars each. I say "on the surface" because I don't know what other terms would apply or exactly how much the shipping would be on a quantity of these, or if there is any additional handling charge. Also don't know if this is a good price for the 1AA, since I paid less than $6.00 for the 1AAA/1LED.

The thought of a group buy entered my mind. I'm reluctant because I've never done such a thing. Also, it appears that group buys usually end up proving – once again – the old adage "No good deed goes unpunished." I may start a new thread to see if there is any interest – I just don't want to commit myself yet.

Re: Dorcy 1AAA 1LED disassembly. Help!

[ QUOTE ]
Doug S said:
Thanks guys for the help. I have it apart. I have reverse engineered the circuit and used a scope to check the waveforms at all the nodes. Here is the kicker, this seemingly simple circuit [6 components, effectively only 5 since two are in parallel] has me baffled. It does not appear that it should work but it does. /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif
If anyone else reverse engineers this circuit, please explain it to me. I am highly embarrassed.

[/ QUOTE ]

I have it figured out now. I am no longer embarrassed but amused instead. The board designers deliberately incorporated a "red herring" on the board as a joke on reverse engineers. I will post the details later as time permits.

Re: Dorcy 1AAA 1LED Circuit efficiency test data

[ QUOTE ]
WayneM said:
Hi Doug S.

First, I'm surprised you haven't been able to find the Dorcy 1AAA in Nashville. I live in North Alabama, and our Wal Marts here don't have them, but last week I was in Lebanon, TN, and picked up on in the Wal Mart there. After using the light I now wish I had bought all they had.



[/ QUOTE ]

This may mostly reflect that it only takes a few Walmart visits for me to lose interest.

[ QUOTE ]
WayneM said:
The thought of a group buy entered my mind. I'm reluctant because I've never done such a thing. Also, it appears that group buys usually end up proving – once again – the old adage "No good deed goes unpunished

[/ QUOTE ]

There is more than a little truth to this. I am thinking of poor Howard that organized a Li-ion rechargeable group buy a while back.

Re: Dorcy 1AAA 1LED Circuit efficiency test data

My original post of test data for this circuit has been extensively edited. I have redone the testing correctly. I originally committed a rather egregious technical error by measuring the input current with a *true RMS* reading ammeter. Where the DC input current has a AC component and the load in not linear [e.g., not purely resistive], computing I/O efficiency with RMS current data is not valid.

Re: Dorcy 1AAA 1LED Circuit efficiency test data

OK, some more test data. The modders looking for a $6 convertor board are going to like this. I tested it driving a fairly low Vf 1W luxeon. At a Vin=3.0V it will deliver 336mA at an efficiency of 70.4%. There is an easy, zero cost mod that will raise the efficiency by about 9% at this output. At a Vin=1.20V it delivers 73.7mA and at 1.30V in delivers 94.3mA. Cheap 1AAA/1W luxeon mod!

Re: Dorcy 1AAA 1LED Circuit efficiency test data

What about using a AA battery to drive the 1W ??

Re: Dorcy 1AAA 1LED Circuit efficiency test data

[ QUOTE ]
unclearty said:
What about using a AA battery to drive the 1W ??

[/ QUOTE ]

[ QUOTE ]
Doug S said:
At a Vin=1.20V it delivers 73.7mA and at 1.30V in delivers 94.3mA.

[/ QUOTE ]

This looks favorable for a 1AA with 1W mod.