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Re: Add LED work tool lights and automatic charge monitors

Posted: Fri Aug 14, 2015 2:35 pm
by burger2227
I have a Dust Buster hand vacuum that uses a plastic flap to keep dirt and bugs in the chamber when hung on the wall:
The flap would get stuck open at times and bugs or dirt would fall out when hanging it up. It can't stick up now either.
I found a small hardware hook that added some weight to it when I pasted it to the inside of the flap keeping it closed.
I used my famous clear silicone calking too! It should hold as good as a glue gun would.

The NiMH or NiCad batteries are getting worn out already so I may be following this up with a Lithium battery upgrade soon!
I have batteries and a special charging circuit ready to change it over from 12 to a 11.1 volt Lithium setup.
It should last a lot longer. I also have a charging set up that will stop charging it with LED red to green indicators I may add too.

PS: Dust Busters are great for cleaning up roaches and other big crawling bugs without smashing them!

Re: Add LED work tool lights and automatic charge monitors

Posted: Fri Mar 11, 2016 1:41 pm
by burger2227
Finally got around to upgrading the bipolar, red/green LED in the Black & Decker saw:
This clear bright LED worked the best against other translucent types. Even when brighter than originals.
Here's the old LED:

The charging status stayed red for 2 or 3 hours and I started wondering about the batteries:
Suddenly it turned green with less of the mixed red and green mixed effect before that.
The old bipolar 2 pin LED was similar when green :

Monitoring battery charging. Rectified + charging voltage is compared to battery voltage
separately so that the LED will only light while charging and not drain the battery.
Also you may want to use a larger value trimmer or add a switch to cut off all drain from the
battery if tool is not used often. A 100K trimmer's current draw is .06 milliamps per 6 volts.
A small relay on the charge voltage could also be added to disconnect the battery fully.

Since my drill charges a detachable battery pack, I have to charge through the drill and remove.
I will add a charge outlet and perhaps a monitor to the battery packs when I convert to Lithium.

The Zener diode's voltage rating should be about half the battery voltage being charged.
This circuit uses a 2 pin bicolored or bipolar LED wired so that it is red when the voltage drops
below a certain voltage and turns green when the voltage is higher. The LM741 Op Amp
output pin 6 goes high when the voltage is higher and low when the voltage is lower.

I found that bad NiMH batteries go green pretty fast when they can no longer hold a charge!
I compared two drill battery packs I had and the newer one took hours instead of 15 minutes.

I will be attempting to make a 12 volt NiMH pack into an 11.1 volt lithium soon I hope.
My B & D Dust Buster is going south so stay tuned...

Re: Add LED work tool lights and automatic charge monitors

Posted: Sat Feb 18, 2017 12:26 pm
by burger2227
While preparing to move I found my old Isotip soldering iron, but the batteries were worn out:
Years ago I had added an SCR LED circuit to the base to indicate when the batteries were charging.
When the iron is first placed in the base, the red LED goes dark or dim when the iron makes proper contact.
Eventually the LED gets brighter when the batteries are drawing little current.

I happened to have a pair of Nimh 1.2 volt, 6000 mah tabbed rechargeable batteries so I replaced them

The large copper plate is pushed down to the + battery button on left to heat the tip and light a lamp.
The lamp gets positive voltage from the copper plate to the side through the bent down tab originally.
The button on left can be unscrewed using needle nosed pliers. I enlarged the + tab hole with a rotary tool.

After recharging the new batteries, I noticed how dull the lamp was compared to a 10 mm bright LED.
The lamp uses .27 amps or 270 milliamps while a simple coil Joule thief circuit uses .04 amps or 40 ma or less.

Problem is that the batteries need to deliver 3 volts, but both only give 2.5 volts max. Needs a Joule thief:
The 5252F chip and a 33 uH coil on right needs to be added to the soldering iron so I removed the button plate.

NiMH denotes the battery required, one or two 1.25 volt rechargeable or 1.5 volt regular batteries.
Do NOT use regular batteries in rechargeable devices!. Pin 1 is used for solar or low +DC charging voltage.

Chip pin 1 is unused and cut off. Pin 3 needs bent back and soldered to the negative bus on right first.
Pin 4 and one end of the coil go to the + side of the lamp base as the bulb bottom is wired to negative bus.

Pin2 goes to other end of the coil and plate. After straightening the lamp tab, the coil wire slid right in.
I didn't even solder the pin 4 coil wire to the plus button plate. It could also have been run to the plate screw.

I broke the old lamp and put a 10 mm white LED in the socket with anode to side and cathode to bottom.
Now I can actually see what I am doing 10 times better using one tenth of the soldering tip current to do so.