12v to 220v inverter 180 watt

Transformerless 12V DC Power Supply

Electric Shock Hazard. In the UK,the neutral wire is connected to earth at the power station. If you touch the "Live" wire, then depending on how well earthed you are, you form a conductive path between Live and Neutral. DO NOT TOUCH the output of this power supply. Whilst the output of this circuit sits innocently at 12V with respect to (wrt) the other terminal, it is also 12V above earth potential. Should a component fail then either terminal will become a potential shock hazard.

Below is a project by Ron J, please heed the caution above and Ron's design notes.

MAINS ELECTRICITY IS VERY DANGEROUS.

If you are not experienced in dealing with it, then leave this project alone.Although Mains equipment can itself consume a lot of current, the circuits we build to control it, usually only require a few milliamps. Yet the low voltage power supply is frequently the largest part of the construction and a sizeable portion of the cost.
This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn't generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or a fusible resistor to be on the safe side. The values given are only a guide. There should be more than enough power available for timers, light operated switches, temperature controllers etc, provided that you use an optical isolator as your circuit's output device. (E.g. MOC 3010/3020) If a relay is unavoidable, use one with a mains voltage coil and switch the coil using the optical isolator.C1 should be of the 'suppressor type'; made to be connected directly across the incoming Mains Supply. They are generally covered with the logos of several different Safety Standards Authorities. If you need more current, use a larger value capacitor; or put two in parallel; but be careful of what you are doing to the Watts. The low voltage 'AC' is supplied by ZD1 and ZD2.
The bridge rectifier can be any of the small 'Round', 'In-line', or 'DIL' types; or you could use four separate diodes. If you want to, you can replace R2 and ZD3 with a 78 Series regulator. The full sized ones will work; but if space is tight, there are some small 100ma versions available in TO 92 type cases. They look like a BC 547. It is also worth noting that many small circuits will work with an unregulated supply. You can, of course, alter any or all of the Zenner diodes in order to produce a different output voltage. As for the mains voltage, the suggestion regarding the 110v version is just that, a suggestion. I haven't built it, so be prepared to experiment a little.

I get a lot of emails asking if this power supply can be modified to provide currents of anything up to 50 amps. It cannot. The circuit was designed to provide a cheap compact power supply for Cmos logic circuits that require only a few milliamps. The logic circuits were then used to control mains equipment (fans, lights, heaters etc.) through an optically isolated triac. If more than 20mA is required it is possible to increase C1 to 0.68uF or 1uF and thus obtain a current of up to about 40mA. But 'suppressor type' capacitors are relatively big and more expensive than regular capacitors; and increasing the current means that higher wattage resistors and zener diodes are required. If you try to produce more than about 40mA the circuit will no longer be cheap and compact, and it simply makes more sense to use a transformer

Transformerless 5V DC Power Supply

Transformerless 5V DC Power Supply

This board takes AC mains input from 100V to

250V AC and output regulated +5V DC providing

current up to 50mA. Great for running small

and almost zero heat generation.

In most non-battery applications, the power to the

microcontroller is normally supplied using a wall

mounted transformer, which is then rectified,

filtered and regulated. In most applications, this

method of generating the regulated voltage is

cost effective and can be justified. However,

there are applications where the main controller

and low voltage is not required by other

components except the microcontroller in

application. In these instances, the cost of the

transformer becomes the sizable cost factor in

the system. For example, most fire alarms &

round the clock monitoring alarms are powered

this way.

Transformerless power supplies, thus, have a distinct advantage in cost as well as in size. The

disadvantages of using a transformerless power supply are low current supply and no isolation from

the AC line voltage.

The microcontrollers usually draw a maximum of 20 mA, even at the highest frequency and voltage

of operation, therefore low current availability is not an issue. The main disadvantage of

transformerless supplies is that they don't offer isolation from the HV line.

One down side of this circuit that it is not isolated from mains so it should not be used in

applications requiring touch of any contact from user. If any part even though +5V side is touched it

would cause shock to the user. Please be careful about touching when using it during experiments

or final applications.

Warning! An electrocution hazard exists during experimentation with transformerless circuits that

interface to AC mains wall power. There is no transformer for power-line isolation in the circuit, so

the user must be very careful and assess the risks from line-transients in the user’s application.

An isolation transformer should be used when probing the circuit during experimentation.

WATER-LEVEL CONTROLLER

WATER-LEVEL CONTROLLER:

K.P. VISWANATHAN

Here is a simple, automatic waterlevel

controller for overhead tanks

that switches on/off the pump motor

when water in the tank goes below/

above the minimum/maximum level. The

water level is sensed by two floats to operate

the switches for controlling the pump

motor.

Each sensors float is suspended from

above using an aluminium rod. This arrangement

is encased in a PVC pipe and

fixed vertically on the inside wall of the

water tank. Such sensors are more reliable

than induction-type sensors. Sensor

1 senses the minimum water level, while

sensor 2 senses the maximum water level

(see the figure).

Leaf switches S1 and S2 (used in tape

recorders) are fixed at the top of the sensor

units such that when the floats are

lifted, the attached 5mm dia. (approx.) aluminium

rods push the moving contacts

(P1 and P2) of leaf switches S1 and S2

from normally closed (N/C) position to

normally open (N/O) position. Similarly,

when the water level goes down, the moving

contacts revert back to their original

positions.

Normally, N/C contact of switch S1 is

connected to ground and N/C contact of

switch S2 is connected to 12V power supply.

IC 555 is wired such that when its

trigger pin 2 is grounded it gets triggered,

and when reset pin 4 is grounded it gets

reset. Threshold pin 6 and discharge pin 7

are not used in the circuit.

When water in the tank goes below

the minimum level, moving contacts (P1

and P2) of both leaf switches will be in

N/C position. That means trigger pin 2

and reset pin 4 of IC1 are connected to

ground and 12V, respectively. This triggers

IC1 and its output goes high to

energise relay RL1 through driver transistor

SL100 (T1). The pump motor is

switched on and it starts pumping water

into the overhead tank if switch S3 is ‘on.’

As the water level in the tank rises,

the float of sensor 1 goes up. This shifts

the moving contact of switch S1 to N/O

position and trigger pin 2 of IC1 gets connected

to 12V. This doesn’t have any impact

on IC1 and its output remains high

to keep the pump motor running.

As the water level rises further to reach

the maximum level, the float of sensor 2

pushes the moving contact of switch S2

to N/O position and it gets connected to

ground. Now IC1 is reset and its output

goes low to switch the pump off.

As water is consumed, its level in the

overhead tank goes down. Accordingly,

the float of sensor 2 also goes down. This

causes the moving contact of switch S2 to

shift back to NC position and reset pin 4

of IC1 is again connected to 12V. But IC1

doesn’t get triggered because its trigger

pin 2 is still clamped to 12V by switch S1.

So the pump remains switched off.

When water level further goes down

to reach the minimum level, the moving

contact of switch S1 shifts back to N/C

position to connect trigger pin 2 of IC1 to

ground. This triggers IC1 and the pump is

switched on.

The float sensor units can be assembled

at home. Both the units are identical, except

that their length is different. The depth

of the water tank from top to the outlet

water pipe can be taken as the length of the

minimum-level sensing unit. The depth of

the water tank from top to the level you

want the tank to be filled up to is taken as

the length of the maximum-level sensing

unit. The leaf switches are fixed at the top

of the tank as shown in the figure.

Each pipe is closed at both the ends by

using two caps. A 5mm dia. hole is drilled

at the centre of the top cap so that the

aluminium rod can pass through it easily to

select the contact of leaf switches. Similarly,

a hole is to be drilled at the bottom

cap of the pipe so that water can enter the

pipe to lift the float.

When water reaches the maximum

level, the floats should not go up more

than the required distance for pushing

the moving contact of the leaf switch to

N/O position. Otherwise, the pressure on

the float may break the leaf switch itself.

The length of the aluminium rod is to be

selected accordingly. It should be affixed

on the metal/thermocole float using some

glue (such as Araldite).

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