Electrical Engineering

Questions tagged [transformerless]

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Transformerless power supplies produce a low voltage from AC mains without using any kind of transformer and without providing any safety isolation.

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4answers
187 views

An inverter without a transformer?

I am trying to build an inverter without a transformer. I want to use a 12V battery connected to a boost converter which will boost the 12V to 120V, then simply attach an H-bridge to the 120V boost ...
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1answer
108 views

Rectified 230VAC to 24VDC

I am building a simple motor control application, driving a series wound motor that runs on rectified 230VAC. Originally, it was controlled by a pendant switch connected to a 7 pin connector. The idea ...
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0answers
50 views

How to build a simple 12VDC-12VAC transformerless inverter using transistor

I am looking for a circuit diagram or an explanation on how to build a 12VDC-12VAC inverter circuit without using a transformer or an inductor of any kind. I want this circuit to be as simple as ...
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2answers
108 views

Can we make a transformerless 220V to 12V converter without a Zener doide?

I saw many circuits have a Zener diode, but a guy from Youtube lighted up a 12V LED without a 12V Zener diode in the cicuit. How is that?
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3answers
81 views

Capacitive dropper power supply for LED - zener/decoupling capacitor?

Let's say you have a standard capacitive dropper power supply like the following (from Wikipedia): I understand that these work well for driving LEDs since they act like a constant current source. I ...
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2answers
130 views

Capacitor protection in transformerless power supply

I am designing a capacitor based transformerless power supply for a WiFi-based device which will be on for 24x7, with an input of 230VAC at 50Hz. For almost 80% of the time, the device would consume ...
1
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1answer
126 views

Voltage dropping capacitor doesn't drop the voltage?

I am going to make a transformerless power supply. Here I am using a 105J 400V polyester capacitor to drop the voltage. I connected the capacitor and AC main in series, but when I measure the voltage ...
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0answers
43 views

Is it possible to connect a switching buck converter to a simple transformerless power supply?

Many cap based transformerless power supplies intended to use with 5V circuits, use a 5.6 zener diode to regulate ouput voltage. I'm using below circuit and the calculator here [which is based on the ...
1
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1answer
59 views

Why using capacitor in transformer less ac to dc converter

I saw many transformer-less power supplies using capacitive resistance of a capacitor. But I don't know exactly what the reasons are for using capacitors instead of normal resistors . I guess two ...
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1answer
148 views

What kind of power supply is best for IoT application?

I am trying to make some IoT devices to fit in wall outlet. There is an issue with power supply. I have to feed my circuits from 220V outlet and there is a limitation in size. I tried to use some HLK ...
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2answers
220 views

6.2 V zener shows lower voltage (Multisim)

I have this circuit with a 1N4735A 6.2 V zener diode. I am trying to figure out why am I measuring 5.1 V across it. The circuit is a transformerless power supply with more or less 60 mA of maximum ...
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2answers
215 views

Capacitor Vrms vs Vpeak Rating in Transformerless Supply

Why is it that when calculating for voltage across the capacitor in transformerless power supply we need to use peak voltage not RMS voltage value. To be clear I am referring to the rating of C1 in ...
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0answers
51 views

Capacitive Power Supply Torch

I'm an amateur at electronics circuitry and concepts. I have designed a simple capacitive power supply using few web images and brief lessons. I understand that this type of transformerless power ...
2
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1answer
265 views

Adding ethernet jack and transformer to device designed without one

I'm attempting to add an RJ45 Ethernet jack to a commercial device without one by replacing an embedded WiFi module, which, according to its datasheet, is connected to the rest of the system as ...
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1answer
205 views

Transformer less Power supply's waveform is Noisy

Hi I want to measure the mains voltage using transformerless power supply. the output of the supply is fed to an optocoupler and later read by a microcontroller. The problem i am having is that the ...
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5answers
545 views

Resistor & capacitor are getting too hot

I made a transformarless power supply with capacitor. When i connect it on ac, it light the leds. But after some second the 100ohm resistor and 470uf capacitor get too hot. Its too hot that i could ...
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2answers
112 views

How to obtain 360vdc from 240vac for audio use without a transformer?

I'm in the process of creating a tube guitar amplifier with an output power of ~6w (fender vibrochamp AA764) which requires the use of 360-400vdc. How could I obtain such a voltage from mains without ...
0
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1answer
96 views

+/- 96 V transformer less power supply design

I know this is a dangerous practice, but obtaining a transformer to make a vacuum tube power supply in my country is prohibitively expensive. So i have to go for transformer less psu. I am just making ...
1
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1answer
231 views

Modify Transformerless Power Supplies

Based on this article: https://hackaday.com/2017/04/04/the-shocking-truth-about-transformerless-power-supplies/ I have some rf wireless plug outless which use transformerless power supply. I would ...
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2answers
92 views

Prevent transformerless powerless supply going full voltage on O/P in case of open circuit

I would like to automate two of my lights using Nodemcu and a 5 V relay board. I am planning to power the relay and Nodemcu with a transformerless power supply. Is there a way to prevent full voltage ...
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1answer
115 views

What resister I want to use to drop voltage for LED? [duplicate]

I am going to connect 10 led in series without a transformer. Now I want to know the value of resister to connect 10 led in series and please give the calculation method thank you.
0
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1answer
309 views

What types of signals can a dynamic microphone generate?

And what design generates what type of signal property? For example there are dynamic mics with or without output transformers. Do they differ in the type of signal outputted? Do most dynamics ...
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7answers
6k views

Transformerless power supply

I'm looking for building a power supply circuit that will convert 230VAC to 5VDC in order to power up an Atmega328P. I also want this to be as small as possible. I know a transformer is one option ...
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1answer
105 views

Transformerless supply [closed]

I am desigining a transformerless supply with two cap in series .if I measure the voltage across 1st cap it is 80 volts and same for other but net voltage measure across these two caps are 240 How and ...
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3answers
369 views

2kV AC step down to 5v without using transformer [closed]

I'm doing an industrial project, i need to step down the high voltage of 2kV to 5V, is it possible to step down to around 5V without transformer, is there any other alternatives? please suggest me :)
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2answers
3k views

ATtiny13a capacitive power supply

I would like to power my Attiny13a MCU with a transformerless capacitive power supply. The MCU itself needs only a few milli amps and it will drive 2 LEDs at 15mA each through it's digital pins. So I ...
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2answers
189 views

Capacitive Power Supply Zener Resistance

I am designing a Capacitive power supply, I found someone who did the circuit shown in the figure. I don't know what is the usage of the 47 ohm resistor in series with the Zener diode (12V MELF ...
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2answers
792 views

Polypropylene capacitor power supply [duplicate]

I found some articles talking about transformerless power supplies, and I have uploaded the schematic of such a circuit. Does anybody have an idea about the pros and cons of such a power supply? Also ...
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2answers
1k views

LM317 output voltage to 0 V with transformerless negative voltage created through a buck converter

I try to construct a shut down pin or a feature which can set the output of LM317 or LM78XX with negative voltage that is created through a transformerless buck converter. A buck converter having ...
0
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1answer
197 views

Identifying unknown components in transformerless power supply

So my dad found one of these voltage converters lying around. I was quite curious what components it had as it is very lightweight (transformerless) and boasts a good 1600W @ 110vac (14.5A) on the ...
1
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1answer
749 views

Safety of zener diode based non isolated power supplies

Are the following zener diode based non isolated power supplies safe to use with a touch based application? I would assume, the circuits are safe if they completely sealed (including the touchpad). ...
1
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1answer
252 views

Capacitive power supply - Bleeding resistor reliability considerations

We are using a capacitive power supply for one of our applications. The X2 capacitor (330nF in this case) provides good reliability with respect to failing safely/open and good over-voltage ...
21
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8answers
4k views

Two resistors in series

I know the summation equation for two or more resistors in parallel or series, and I know two parallel resistors will give more power. But sometimes I saw some circuits that used two resistors in ...
0
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2answers
1k views

Protect my circuit from overvoltage on AC line

I used this link to generate a 5VDC (1A) from the 220Vac power source, the circuit itself works perfectly fine but i want to make sure that the overvoltage on the AC line won't damage my board. I ...
3
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3answers
4k views

Designing small size AC/DC to provide 3.3 V for MCU [closed]

I have designed ESP8266 based light switch, that is controllable via web page or a push button. Light is being switched with use of Triac (TIC206) through optocoupler (MOC3041). Prototype works as ...
5
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2answers
790 views

Reducing volume for a split-phase 230VAC@60Hz sealed power supply providing 5VDC@50mA

I'm a hobbyist interested in re-designing and implementing a DC power supply providing a \$+5V_{DC}\pm 200mV\$ output with a current compliance of \$50mA\$ (I could live with \$30mA\$ successfully) ...
0
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1answer
2k views

How to calculate output voltage of a non polarized capacitor?

How to calculate output voltage of non polarized x-rated capacitor (230VAC 5A 50/60Hz)? (which depends on input voltage) as like as the calculation of output current here tutorial table here tested ...
2
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2answers
1k views

Isolation of the transformerless power supply

One of the disadvantages of transformerless power supply is the isolation problem because of the absence of the transformer. My question here is : Doesn't the capacitor in series at the input do the ...
0
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1answer
248 views

Can tranformerless inverter topology be used in UPS with a regular battery (12V 7Ah)?

While searching for transformerless inverters in the IEEE site, most of them seem to be about grid connected Photovoltaic inverters. Removing transformers will increase the efficiency at the cost of ...
1
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0answers
206 views

Transformerless Realtime Clock Issue

I have an issue with designing a Real Time Clock by using Transformerless power supply. I don't use RTC IC but I use Microchip PIC instead and 32kHz clock. I use battery of 3.3V for backup supply. The ...
0
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1answer
2k views

Transformerless Power Supply High Current

Is there any way for Transformerless Power Supply to output a High Current like 10A to 15A at 12V to 24V. I found highest of 500mA current output for Transformerless Capacitor Power Supply. I wanna ...
0
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1answer
4k views

Transformerless power Supply - 24VDC, 120V AC and 230V AC

I want to know if it is possible to design a power supply for a circuit that can operate from DC and AC using the same input terminals. Thus, the output should be xxV DC (5-24 or whatever is decided ...
0
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1answer
495 views

Transformerless rectification is giving out AC component [duplicate]

I want to convert 240V AC 50hz to 12V DC without transformer.I want the output (12V) to drive 25 white LEDs.The circuit is giving an output of ~14V DC.But the problem is that it is also giving out ~...
0
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1answer
1k views

Capacitive transformerless power supply, AC polarity problem

I have implemented a "Capacitive transformerless power supply" to control a microcontroller-based circuit that contains capacitive touch sensors, and I had an "AC polarity problem" Surprisingly, the ...
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2answers
1k views

how to design transformer less power supply? [closed]

I want to desgin a 5V,0.5A transformerless supply (minimum components) for mains 100-260Vrms, 45-65Hz? I found several ways to do it which are mentioned below 1. resistive power supply - Microchip ...
0
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1answer
198 views

How can I make a POWER-LED Lamp?

What is the best way to light 10 POWER-LEDs with AC mains (220V)? (I want to make an LED lamp.) Here is more info: I have 10 of these POWER-LEDs: Product Chip: 40x40 mil Chip Brand: EVERLIGHT-...
0
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2answers
13k views

Use of transformer in arc welding

Why transformer is used in arc welding and what will happen when anyone touch the electrode at the time of welding?
4
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4answers
5k views

Surface mount transformerless 230v to 3.3v on a small board

I am trying to design a 3.3V mains power supply to go on a PCB approximately 50x25mm in size (this will include other functions too!). I've come across the Supertex SR086, which is almost perfect, ...
1
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0answers
966 views

Split-phase 230VAC transformerless capacitive power supply for 5V@30mA regulated output — series cap?

I'm a hobbyist developing a hybrid power switch (electromagnetic + solid state) for a resistive electric stove (8kW max) top. I have a profoundly autistic, disabled adult in the house and I need a ...
3
votes
2answers
3k views

Designing a Transformerless power supply

I am working on a transformerless PSU for maiking a 3nos.x3 watt led, each having forward voltage around 3.6v and current around 650-700ma. I have worked on this kind of circuit: I guess a 1uf ...

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