High everyone!!!!
In this article, I will show how to step-down AC for higher current output without using a transformer.
This circuit is meant to work for only AC operating motors!
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This is a common question, being asked by many newbie (even by me also) but answers are hard to find. One day I sort out the possibility when I looked a scrap circuit. That circuit is very common to all of us.
This circuit is meant to work for only AC operating motors!
``````````````````````````````````````````````````````````````````````````````````````
This is a common question, being asked by many newbie (even by me also) but answers are hard to find. One day I sort out the possibility when I looked a scrap circuit. That circuit is very common to all of us.
In this method, I will use a triac to minimize the voltage. This circuit can be used for a power consumption of about 100W or more, depending on the size of heat sink you are using.
TRIAC or Triode for Alternating Current is an electronic component that can conduct current in both directions when it is triggered (turned on). These are considered as an AC switch. The gate current to trigger the triac can be as low as 10mA to 50mA and increase in gate current will increase the voltage output. The output voltage can be as low as 5V AC and as high as 220V AC.
Below is the schematic of a voltage controller:
Here DB3 is a DIAC which can only supply a voltage greater than 30V. It is used to make an operational limit for the output of the triac. If mains voltage falls from 220V and the gate voltage is lower than 30V, the circuit will break. However, you can remove the diac if you are working in a low mains voltage or want to drop the triac’s output very low. R5 is a current limiting resistor and is optional.
To increase the output, you have to decrease the value of R2 or R4, and vice versa.
Component details:
3. Triac = BT136 or equivalent
4. Diac = DB3
5. R1 = 68Ω 1/4W
6. R2 = 5.6KΩ 1/4W
7. R3 = 750KΩ 1/4W
8. R4 = 600kΩ potentiometer
9. L1 = 100uH
Note: This schematic is designed by me and I will not guarantee for any malfunctioning and damages of components. This is a high voltage application and proper precautions should be taken.
Hi,
ReplyDeletegood for AC motors. What can I do for DC motor high current - low voltage from mains without using transformer as well?
Possible to add a rectifier in output this circuit? or what else?
Thanks
For high current application in low voltages, it is not wise to use triac as this will create a lot of EMI. No matter you use any transistors or ICs, the best option is to use a transformer. Only a trafo can down-convert power efficiently. And as you get your maximum volts for your motor, you can then use PWM to control its speed. If using an iron core trafo for 50Hz consumes a lot of space, you can look for ferrite trafo and use 100 to 200kHz for step-down. Ferrite trafo consumes unimaginably very small space (say size of a 1000uF electrolytic cap) and can deliver a lot of power.
DeleteThe circuit you showed here is inside every cheap fan regulator having pot to adjust triac firing
ReplyDeleteStep-Down Transformer is the one that converts a high-voltage and low-current into a low-voltage, high-current power. These are mostly required in the domestic consumption. These are designed to withstand electrical impulses and thermal and dynamic stresses. It ensures low power loss, low maintenance cost, and low noise.
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Thanks for Sharing this useful information with us.
ReplyDeleteTransformer Manufacturers In India | Transformer Manufacturers In Mumbai
You don't need to do any repairs. New introduces accompany guarantees on parts and administrations. You should simply call up a specialist. furnace repair patterson
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