It is the desulfator/charging circuit from Mikey Sklar's open-source DA PIMP 2 ("Power In My Pocket") without the voltage meter circuit.

DIMP 1 EXPOSES THE USER TO LETHAL VOLTAGES. DO NOT buy or build one if you will not take full responsibility for using it safely. Follow Mikey's instructions for use religiously. Neither Mikey Sklar nor I take any responsibility for your use or misuse of DIMP 1. If you have young children, you probably should not have one of these in your home, just in case they find it and plug it in without knowing what it is.

I designed DIMP 1 for several reasons:

1) Added Neon Lamps

DIMP 1 features two neon lamps to improve safety. They are not a guarantee of safety--it is still possible to get a nasty shock if the lamps are off, and if one of the lamps is broken, there is the potential for lethal shock. Always keep clear of the output leads whenever the AC mains are connected.

NE2, the lamp near the output end, turns on when these potentially lethal conditions are met:

+ DIMP 1 is connected to AC mains.

+ Rocker switch is turned on.

+ Output leads are not connected to anything OR the battery is offering too much resistance.

In these conditions, there is lethally-high voltage at the output leads.

If there is no voltage at the output leads but NE2 is lit, the fuse is either blown or loose in the fuse clip. Treat the output leads as if they are still exposing lethal voltages to the user, because a loose fuse might suddenly start conducting. Turn off the rocker switch and disconnect the AC mains before handling the leads or opening up the DIMP 1 to check on the fuse.

NE1, the lamp near the AC mains port, turns on when these potentially lethal conditions are met:

+ DIMP 1 is connected to AC mains.

+ Rocker switch is turned on.

+ Output leads are connected to something offering low resistance, which could be a non-broken battery being charged or desulfated. The potential danger is if the output leads are connected to the wrong thing, such as a person or a metal rod or each other.

DO NOT DEPEND ONLY ON THE LAMPS FOR YOUR SAFETY. KEEP CLEAR OF THE OUTPUT LEADS WHENEVER THE AC MAINS ARE CONNECTED TO DIMP 1.

REPLACE THE NEON LAMPS WHEN THEY BURN OUT.

2) New Rocker Switch

Mikey's DA PIMP 1 and 2 both required a very-hard-to-get Schurter DPST rocker switch that is now quite expensive at over $11 each. I chose a widely-available and lower-cost (~$3) Omron switch to replace it.

3) Removed Inaccurate and Slow Voltmeter

The voltmeter circuit in DA PIMP 1 and 2 is surprisingly inaccurate and slow. (See Mikey's source code for the multipliers he used to try to make it more accurate.) I had to use a separate pocket multimeter for more accurate and faster readings.

Removing the voltmeter circuit saves about $15 in parts and $20.00 for an AVR programmer and avoids the hassle of programming the ATMEGA48V. Assembling the DIMP 1 circuit is just soldering the components in place.

4) Safer and Easier Switching of Output Current

DA PIMP 2 used two jumpers for changing the output current for different types of batteries. I found these to be both cumbersome and dangerous to remove or replace, so I replaced them with slider switches.

5) Better and Smaller Housing

DA PIMP 1 and 2 both used a soap box as a housing. I designed DIMP 1 to fit in a commonly-available Hammond Mfg. 1591-series project box less than half the footprint of the original DA PIMP.

6) More Versatile Hook-Ups

DIMP 1 has one red-black pair of 4mm banana jacks and one red-black pair of 2mm test jacks that can be used for hooking up batteries and multimeters.

These jacks make it possible to use widely-available test leads with a variety of heads. For instance, for safer handling, you can use sheathed 4mm banana jacks and get sheathed alligator clips. Or you can get pincer or hook clips. (The BOM includes affordable non-sheathed leads by Sparkfun; switch these leads out with your preferred leads such as Pomona or Cal Test brand leads.)

NOTES:

A) DANGER: LETHAL SHOCK HAZARD!!!

It bears repeating: ALWAYS KEEP CLEAR OF THE OUTPUT LEADS WHENEVER THE AC MAINS ARE CONNECTED TO DIMP 1.

B) READ THE INSTRUCTIONS BEFORE USE

The instructions are roughly the same as for DA PIMP 2. Be sure to read them and understand them fully so that you know what to expect when using DIMP 1.

The main difference between DA PIMP 2 and DIMP 1 is that for DIMP 1 you must provide your own multimeter and you can use the slider switches instead of the jumpers to change the output current.

Mikey's instructions are at screwdecaf.cx.

C) ASSEMBLY IS DIY AND THERE IS NO WARRANTY!!!

BILL OF MATERIALS

You can order almost all the parts to build DIMP 1 from Mouser. The only parts you can't get from Mouser are:

a) the test leads with sheathed 4mm banana jacks and fully-insulated alligator clips. You could try these if you aren't sure what you want, but the leads are quite long:

https://www.mouser.com/ProductDetail/cal-test-electronics/ct3803-60/?qs=dJUxbiCuMc43CuJnPzeX6w%3D%3D&countrycode=US&currencycode=USD

b) four #4 x 1/4in. self-tapping screws to attach the PCB to the enclosure. 

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=4fcb841be7

Alternately, here is the BoM.

DIMP BOM 1591XXM WITHOUT OUTPUT LEADS    

Mouser #, Mfr. #, Manufacturer, Description, Order Qty.

611-L202031MS02Q, L202031MS02Q, C&K Switches, Slide Switches SLIDE SWITCH, 2

510-CT3151SP-2, CT3151SP-2, Cal Test Electronics, Test Plugs & Test Jacks SafetyJack,Horz PCB, 1

546-1591XXMTBU, 1591XXMTBU, Hammond, Enclosures, Boxes, & Cases Translucent Blue Box 3.3x2.2x0.9" ABS, 1

510-CT3151SP-0, CT3151SP-0, Cal Test Electronics, Test Plugs & Test Jacks SafetyJack,Horz PCB, 1

576-01110501Z, 01110501Z, Littelfuse, Fuse Clips ACS 2AG PC MNT CLIP, 2

530-2JQ3-R, 2JQ 3-R, Bel, Cartridge Fuses, 3

833-UD4KB100-BP, UD4KB100-BP, Micro Commercial Components (MCC), Bridge Rectifiers 4A, 1000V Bridge Rectifier, 1

562-770W-X2/10, 770W-X2/10, Qualtek, AC Power Entry Modules RECEPT PANEL R/A PCB, 1

667-ECW-FD2W475K, ECW-FD2W475K, Panasonic, Film Capacitors 450VDC 4.7uF 10% MPP L/S=22.5mm, 3

653-A8L-21-12N2, A8L-21-12N2, Omron, Rocker Switches ROCKER SWITCH, 1

552-AC15WNA-R, AC15WNA-R, Phihong, AC Power Cords 2-WIRE AC CORD, 1

530-105-1102-1, 105-1102-001, Cinch Connectivity Solutions, Test Plugs & Test Jacks TEST JACK RED, 1

530-105-1103-1, 105-1103-001, Cinch Connectivity Solutions, Test Plugs & Test Jacks TEST JACK BLACK, 1

696-GT-NE6S1325T, GT-NE6S1325T, Lumex, Lamps Neon Lamp Standard Brightness, 2

660-MF1/2LCT528R224J, MF1/2LCT528R224J, KOA Speer, Metal Film Resistors - Through Hole 220K ohm 5% 200 ppm AEC-Q200, 2

For assembly and usage instructions, see:

https://www.instructables.com/id/DIMP-Desulfator-in-My-Pocket/

Feel free to contact me with any questions before or after your purchase.

Ships 2oz. USPS First Class Package