Wednesday, November 23, 2011

Under voltage detector with optocoupler

You can use any kind of load: relay driver, fet switch, LEDS, bulb and more. Design the load driver so the optocoupler is driver for the 'driver transistor' ;)

This circuit can be used as undervoltage detector for LiPo batteries, Li ion bateries and more.

I use this circuit in my automatic grid of offgrid power strip

Monday, November 21, 2011

step up converter lm2577

Update 25-12-2011: added a 3k9 resistor in series with the trimpot, the trimpot burned at low resistance

lm2577 step up converter to be used for my TEG peltier power generator mountet on my pellet boiler.

I decided use this step up converter schematic as base circuit:

Works in first take ;)

This is the modified version of the circuit where i added 3k9 resistor:

I started placing components on the schematic:

Cut out a smal pcb

Mont all the parts

 12 volt DIY LED feeded from 3,5 volt supply. Could be a Li Ion or LiPo cell

I works, but i am not satisfied with the performance. There are lot of lost power in power conversion with this chip, as i only has a standard NPN transistor as switcher instead of a MosFet.

So i will DIY my own switcher circuit for my TEG ;)

Sunday, November 20, 2011

Pellet boiler produce electricity

The peltier elements (the white layer between the copper plates) are placed between cobber top plate with pipes for cooling water inside

This show the power block with step up converter. Made to stepup from 1,5 volt tol 9 volt to charge a 6 volt akku.

I found a cheap vaterpump wheel i will try to use in a more power full water cooler driven by PMM with neuro magnets:

Saturday, November 12, 2011

220 volt Optocoupler detector for arduino

Optocoupler detector for 220 volt

I used a optocoupler from a defect switchmode supply p621

220 volt single LED

Gridtie solar power supply

Maximum performance was 471 watts a sunny winter day here in Denmark. The total power from 2 pcs 190 watt ulica solarpanels are 1140 watts. So 471 watts are great winter power i think. I use 375 watt in average every hour, so just a little sunshine in the daytime, and my electricity needs are meet.

Monday, November 7, 2011

Switch between Offgrid inverter and gridtie

This power strip has building automatic switch between offgrid power and gridtie power.

When i turn on this power strip it automatically detects lowvoltage on tofgrid batteri'es, and chose to turn on the inverter or switch on relay to grid as power source. Also, if low voltage is detectected when i watch television, i switch to grid from offgrid, an stay gridtied to next time power strip is turned on.

To stay safe it has build in two optocouplers, to protect agains 220 volt in the 12 volt offgrid system.


Link to the under-voltage detector circuit

The control circuit on pcb: 

This is how i works:

Be careful, there is danger of electric shock, and at worst you can die from it. I myself disclaims any responsibility for your experiments.

In some countries it is not allowed to work with diy stuff connected to the grid, and other things connected to the gridIn some countries there is some national wiring regulations to be observed.

The idee in blocks

My 12 volt to 220 volt inverter:

The power strip and the inverter

I tryed to yúse a simple Set / reset flip flop with transistors, to hold relay, but it was unstable, so i desided to use a small relay with low power consumption instead. You can try to build this circuit to experiment with transistor based set reset logic:

Sunday, November 6, 2011

Electric bicycle diy

This is a Old arrowhead GT mountain bike, but not used a lot.

It has aluminium chassis, and is light weight. Wheels are 26".

I will convert it to electric bicycle.

Step conversion DIY guide

  • Make a simple DIY PWM DC moter controller with FET from scrap components, Done 
  • Make a some kind of magnetic sensor (hall) that can measure than the pedals run round
  • Make some kind of brancket for the motor, and batteries
  • Make a 24 Volt battery pack from scrap Laptops Li-Ion bateries
  • Make a 24 Li Ion Charger with temperature sensor, anti fire protection and more

Thursday, November 3, 2011

buck boost inverter for solarcels and peltier power

his article is my workbench 'Notepad' as i learn and build a buck bost inverter for low voltage from peltier elements seeberg effect (thermoelectric elements) and solarcells.

Both power sources give very low voltage: solarcells typical 0,5 volt and peltier elements 0,5 - 1-2 volts.

My goal is to charge directly on a standard acid battery, both 6 volt and 12 volt.

Latter i will add a Li Ion / LiPo single cell charger and a charger on mulitible Li cells cells

Project start

I've saved some defective PC computer power supplies for spare parts, they have quality great coils and more.

I believe i can find all parts needed on these pcb's to build my buck boost chargers

Chips found on deffective boards:

I believe the top210pfi is the best choose because it has a build in MOSFET, that means less components in the final buck boost circuit.

But first i might need to make a LC meter to measure coils Henry value.

nice and easy inductimeter project, i choose to build this one 

Building the Inductimeter

Links and ressources about buck boost:

transistor baseret, ingen trafo:
fet baseret, ingen trafo:
Boost moduler:


Tuesday, November 1, 2011

Step up converter 12 volt to 24 volt dc

This a solarpanel mppt charger for 18 volts DIY solarpanels charging 24 volt batteries, It properly can be changed to charge 12 volts bateries as well. The circuit use a uc3842. this chip can be found i scrapped switchmode supplyes from outdated Computers.

I found the schematic for stepup converter 12 volt to 24 volt here


  • Version 1.0: this version i not covered on this site you can follow the 12 volt to 48 volt solarcharger stepup converter here
  • Version 0.8 beta: The version below show my first stepup converter experiment with uc3842. I 'killed' 2 uc3842 in my experiments increasing output voltage to 48-60 volt for my EV, så desided to build a new version, version 1.0

It works as expected, mppt starts charge at 15 volts, not sure why not 10 volt, but output voltage is stable 24 volt. When i turn input voltage up to 20 volt still 24 volt output, i turn down insteps to 10 vlt, still 24 volt output, and when i stay between 10 volt and 20 volt it works totaly as i expected, Great mppt to my diy solarpanels ;)

Some link and ressources: