Monday, October 31, 2011

Dc to dc inverter from 1,5 volt to 9 volt

Original Schematic to this simple and effective switcher can be found here:

I decided to make a MosFet based version for better performance. Update follw later opn this subject ;)

peltier cooling box

Found some interesting movies on youtube, showing how peltier are used to make DIY cooler box. This is exactly hox small 12 volt coolers for use in cars are made.

Think i will experiment with my fridge, build in som peltiers to help the compressor to cool down food with cheap DIY solar panels.

Saturday, October 29, 2011

Gridtie solarpower getting ready

Removing my offgrid solar installation, cleaning up and preparing the space for my gridtie solarpower inverter from exendis.

Saturday, October 22, 2011

Under voltage detector li ion added trimpotmeter

I added a thermal switch from a defect power amplifier, to shutdown power drill tool, i overheaded.

The circuit works and disable the out put when voltage from battery get down to 12 Volt and  below

Circuit cut of the load until Li ion battery are re charged

I added a trim potmeter to make the adjustment easyer, i will glue the trim pot to hold the setting.

Friday, October 21, 2011

Under voltage detector Li ion and lipo battery

You Must read this before you read this post: 

24-10-2011: update, the P-fet burned one more time today, so i search my scrap box now for a more powerfull fet. So, don't use the TPC8107 P-fet. .

I found that IRF 9540 placed on a cooling plate below the battery works, but think a more powerfull mosfet without cooling plate would bee the best solution. But, i don't have any super power p-fet in my scrap box. And go buy a P-fet, no thanks ;),  more likely i will devel something else latter, for now, this project is ended.

Fell free to share your experiences if you deside to 'hack your screwdrier mashine' :)

22-10-2011: Update, just added a thermal switch on the mosfet transistor, because i burned it. The mosfet get very hot..... I used a 139 celcius themal switch from a defective  Li Ion batery from a ACER labtop comnputer...


If you make experiment with Li Ion nad LiPo bateries, YOU and ONLY you is the one taking the chance, LI Ion /LiPo cells might explode or turn into flammes !!!

I hereby disclaim all responsibility for your experiments. 

 If you expect this is 100% safe, then don't make this hack yourself. 
Go purchase a new battery !! 

 If you will make this Li Ion Hack yourself, then YOU are responsible for all Risk i the project.

And YOU must take responsibility if something goes wrong.

I disclaim all responsibility for your experiments with Li Ion and LiPo cells. 

Li Ion / LiPo cells might explode, and they might turn into flames and burn your house down. 

Mosfet transistor used is from a scrapped Li Ion battery Labtop, a TPC8107

Low Cutoff voltage is 3 volts per cell, that is 12 volts for the 4 cells in this hack.

High Voltage from the newly charged battery is 16.2 volts

Bosch screwdriver mashine can handle 14.4 volts

I use power diodes to bring voltage down to 14.4 volts

Each diode has a voltage drop of 0.6 volts which is used to voltage down to the DC motor inside the bosch psr1440.

Unfortunately there will be some loss of effect which is converted to heat, but compared to that you get a free Li Ion battery in this screwdriver maschine, then I never mind ;).

16.2 to 14.4 = 1.8 volts
1.8 / 0.6 = 3 diodes

The components of this hack comes from defect Li Ion battery from DELL Labtop and the TL431 comes from a dead psu from a desktop computer.

Tuesday, October 18, 2011

Coil Induction meter

Updated 8. december 2011: This was my first try to make a cheap induction meter, but i did not work, so i made a 555 based induction meter instead

Hack your Defective bosch screwdriver

Often it is just a NiCd cell is defective. New NiCd or NiMH cells can be purchased on eBay or the fore peanuts. Alternative, a scrapped computer Labtop Li ion battery do wonders ;)


Here is the battery pack, the next will happen now is to create a sensor that shuts off the battery by Vlow, so the battery does not take permanent damage. Li Ion batteries do not tolerate deep discharge.

Furthermore a voltage regulator must be used as the voltage exceeds14.4 volts and the DC motor will burn out quick.

So lets go to the Diy Li Ion and LiPo Under voltage detector and regulator schematic and project post






Wednesday, October 12, 2011

Monday, October 10, 2011

Fluke 8050A repair lcd display

I got this old fluke multimeter with defect display and not work paying to get repaired with newLCD display.
Defect LCD display in this fluke is a common failure, but no spare part avaiable online.

Found this link:

This guy repaired his fluke with 7 segments LED's display.

I desided to try this fix, and a had a old useless TRIAX TTR120 mpeg 2 tv digital tuner, i desided to hack it and make a LED 7 segment transplantation. I killed the triax tuner, removed the display board and found the datasheet for 7 segments here: LIM-5622G 7 segment display green light. These 7 segment LED's have nice big bright LEDS.

The dual seven segment LED display LIM-5622g is a common anode type as used in the hack. Don't know the current, voltage is 2-2,5 volt, curent properly 10-20 mA cause this is normal. I will come back to test this spec latter.

Started to removed the old defect LCD display.