Inverters for the Light:

This inverter will be destined to give 220 volts service to the basic equipments of the house, like domestic appliances and electrical light with bulbs of low consumption. It is assign for a maximum consumption of about 500w. It also has a small meter that provides us information of the consumption.

Power part:       The power part of the inverter consists of: Several electrolytic capacitors to stabilize the voltage, the sensors of power consumption and the power transistors MOS (two groups of 6 transistors in parallel) type IRF 5210 that allow supply a very high current to the transformer. The control of this high current is tested by a resistance shunt of 0,03ohm, a few optocouplers will give the consumption information to the EPROM, and allow to change the type of wave.

If need, this inverter have a battery load regulator with two power transistors type 2SD1193 (darlington) in parallel, and allow to regulate currents up to 10 amperes and one driver transistor type MC141 to sensor the battery voltage.

Inverter for the freeze:

Normaly the freeze has a low average consumption, one freeze type A consumed 80 to 120 w. But the consumption at power up of the freeze compressor (motor) is very high about 1500w and this forces us to prepare one special inverter circuit.

This inverter have a power down control by temperature, and also wend sense low tension in the batteries.  In any case, it is necessary that the user resumes the functioning of the inverter by the push-button.

The thermostat of the freeze (normaly in serie between the power cord and the compressor of the freeze) provides the signal to star up the stage of power of the inverter. So that, if the freeze does not request power from the inverter, this will reduces very much the consumption because not having current to the transformer.

The inverter of freeze has a great transformer type toroidal to provide the sufficient current for the compressor of the icebox. And also have diverse electrolytic big capacitors (aprox. 25.000 microfarads) to stabilize the current.

The start up of the transformer, the control circuit provides one signal during a time of aprox. 2 milliseconds to a group of 4 transistors, to power with a limited current the transformer.  After 0,6 milliseconds of the start these 4 transistors join 10 more transistors to provide a great power of current to the transformer. The result provides us a wave very looked like to the senoidal.

The following image shows us, a tunnel of radiators where aside we have 8 transistors and two power resistors of 25w and 1ohm. And to another side 20 transistors. Three small fans provide air forced for all.

The Control board:     The control board have an oscillator type 555 and the adjustment for the frequency, a binary counter type 4040 and one EPROM whose content possesses the instructions to make the wave form type pseudosenoidal.  This circuit becomes by power regulator type 7805 that must be good refreshed because the circuits not consumed too much but the tension difference from 24 to 5 volts makes him remove something of heat.

The remote control for the freeze have a small relay of 5 volts stabilized by a condenser of very high capacity 4,7mF (millifarads), a  Zener diode to control the minimal tension of batteries, the push-button  “P”  for start up, the main switch  “I”  to power off the equipment, one thermal switch for protection and the connection for the thermostat of the freeze. This circuit also allows us to protect the deep discharge of the batteries.  In our case the tension lower than approximately 20 volts in the batteries (according to the value of the zener) makes the equipment stops working.

The EPROM:

The eprom contains the necessary information to realize a wave almost senoidal. Of the whole content of the eprom, we only use 64 directions, and in each direction we use the bits 0 and 1 for the 20 transistors of the principal power and the bits 2 and 3 for the 8 transistors that start up the transformer.

The bits 2 and 3 provides a signal of activation for 4 transistors and power on  the transformer during 2 times of EPROM (aprox. 0,6 milisec.), with a current limited by resistors of 1 ohm and 25 w during 7 times of EPROM (2,1 milisec.). Those resistors must be join the radiator because warms.

After 0,6 milisec, the bits 0 and 1 gives power to the principal transistors, 10 for each side of the transformer, which they will give the maximum of current. 

Batteries container and the load regulator: The batteries container has two batteries of 12v and 90 Amp. The load regulator, which mission is it of not giving current to the batteries when are full loaded.

The voltage of max. load is adjusted.             

And one fuse protection of 40 Amp. At the exit of the batteries.