Variable Bench power supply
This is my variable bench power supply!!
it gives an output from 1.24 v -28.4 v dc , a 12 volt output and a 29 v
it is a switch mode supply which makes it lighter to carry , a 24 v smps is used as initial power supply then a lm317 based variable regulated supply circuit is added to it.
Upgrades----> add a precise potentiometer to get a precise output.
P.S.-- this supply also gives a constant current supply for led and battery charging!!
Components Required:-
- DC-AC Converter
- Voltage Regulator
- Enclosure
- Switches, Potentiometer, Connectors and Indicators
Lets Start Building!!
First Step:-
We need to convert AC-DC for that we could use various things. if we want to make "linear" power supply, we need to use a transformer or a switch mode power supply(SMPS).
There are variety of transformer available in market and of different shapes (toroidal or normal). To choose a transformer, first check out your requirements as my supply outputs voltage between 1.24-30V, so I have to choose the one which outputs approx 30V. The output from the transformer is still AC so we need to make a bridge rectifier using some diodes.
An SMPS could also be used for the purpose, In my case I used a 24V 5Amps SMPS, and turn its potentiometer to max, which then outputs about 29V DC.
Second Step:-
After converting AC to DC we need to regulate it and step down according to our needs.
For that we are using Voltage regulator IC. Some IC's are hard to get from the market so we are using a complete voltage regulator module for our purpose,
There are two kinds of voltage regulators available, Step-UP and Step-Down. Use stepdown module as they are more efficient compared to the others.
For our case we are using a LM2596 based module, which is very cheap, you could get one for you " here " .
Voltage Regulator module contains 2 ports, one for Input voltage from transformer/Smps and other outputs the voltage.
There are various on board pot's on the module which works to step-down voltage and adjust current.
Desolder the on board pot's and attach some bigger one like " these".
The voltage and current could be measured by attaching a small current and voltage display which is available " here "
Third Step:-
The complete mechanism for the lab supply is ready, its just need some enclosure for the completion.
The enclosure shown in the above project is a stabilizer enclosure which is easily available in the market.
Place everything inside the enclosure and the supply is ready to use.
For the connectors we are using "BANANA PLUGS" which are standardize connectors for lab bench supplies and multimeters.
Finalizing Everything and Upgrades:-
Potentiometers available locally are not good for getting a precise output so we used a 10-turn pot to get a precise voltage output, which is available "here ".
We also attach a fuse to the input supply for safety.
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