Circuits FAQ

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Friday, June 12, 2020

Mains Voltage Stabilizer Step up Circuit

i kinda found myself in a place where the voltage is so low (80v-110vAC) and i need to boost it up to 220v so what can i do? i have a burnt stabilizer (that is the electronics part) so i need the electronics circuit to replace the burnt one can Anybody help?

post by FP

here is a circuit i made for you, i am not sure it will work, i hope it will help you learn. part of these ideas are over 20 years old. Stabilizer Circuit

Stabilizer Step up 230V AC 500VA

This circuit is a design i did, not tested by me as yet. It can Stabilize Mains voltage to around +/- 10% . It can be used for both 110V AC or 220V AC inputs with modifications. The Output is 220V AC. There is an overload, under voltage and over voltage trip circuit. With some tweaks and modifications it might work.

Solid-State Stabilizer Step up 110V AC

This circuit is a design concept, not tested by me and i did it just to explain some ideas. The circuit uses opto-coupler MOC3041 of Motorola and the Triac BTA-16-600 of ST as a solid state switch or relay. It also uses the LM324 quad opamp from National Semiconductor which is low power and single supply. As the MOC3041 switches the Triac at zero crossover there is no inter-winding short of transformer on crossover hopefully, the control circuit is designed in such a way that more than one triac will not be turned on at a time, i would like you to give feedback.

One more circuit, this is a bit complicated and it is not tested, it may not work that easy, just refer it to make your own design, it is just a bit of theory and my experience, i may be wrong at a few places.

Electric Circuits


Tuesday, June 09, 2020

Lamp Dimmer DC with L296

I need a simple circuit to drive a 12v DC (4amp) light. But, it needs to dim to 25% over a specified amount of time. Basically it needs to hold at 25% (4v) for a few seconds then fade and increase to 100%(12v) , hold for a second then fade back to 25%.

Here are the electrical specs: - Input 12vDC @ 5amps - Output from 4vDC to 12vDC (amp draw may be as little as 1 amp or as much as 4.5) - Only 1 potentiometer is used to vary the rate at which the voltage changes from 4-12 - It must increase and decrease voltage in a very smooth way, so that it fades the light to 100% and then back down to 25%

mail from JR

I have a circuit in my website that may serve your purpose, visit Power Supplies Section.

There may be some documentation errors in my circuits. If you are used to building and troubleshooting circuits then it is ok.

Switching Battery Charger with L296

Switching Battery Charger with L296

L296 is a switch mode power controller here. In this NTE327 or 2N5038 is used to boost the current output. This transistor is both high current and fast switching. U1A, LM358 measures the load current by reading the voltage across shunt R6 and compared to a current limit setting at R14 using U1B to give a load current control. R7-R8 give a voltage feedback for voltage limit.


Tuesday, June 02, 2020

RS485 Modbus - Wireless Interface

I am working on alarm systems and would like assistance in designing wireless link for the unit, ie sensors to control panel, control panel to monitoring station.

I noticed most of the circuits available on your sites are FM 88 - 108 MHz, which would definitely cause interference. Can you please assist me with this final part of my system.

mail from RT

i would like to know........... The wireless link distance of Transmitter and receiver. The frequency range you want like FM 'n' MHz Are you aware of the regulations of wireless transmission.

What band is allowed in your country and what distance. what type of data needs to be transmitted. If this is for process control, RF should be avoided if possible. You should use 4-20mA current loops, RS485 or IR optics.


You can study these pages ...........

Bridging the gap between Modbus/TCP and Foundation Fieldbus

Foundation Fieldbus

Foundation Fieldbus is a power-ful process automation system which offers numerous advan-tages over conventional techno-logies in terms of production quality and serviceability. But migrating to Foundation Fieldbus often entails changing the entire existing control technology - all the way to the managment level.

Modbus Communication Protocol Suite

"The OMWT-XREC-MOD Wireless Transceiver uses an embedded 100-milliwatt frequency hopping wireless modem that provides communication between a local RS-485 network and a remote network of RS-485 connected devices. The OMWT-XREC- MOD will automatically sense the direction of data flow and switch the RS-485 and radio devices accordingly."

with a RS485 and Modbus Network you can do it.


Thursday, April 09, 2020

Electronics Work Bench

How can I get a software for an electronics work bench for my pc.

mail from EA

I did not understand about the 'electronics work bench' pc based instrument. Try simulation based virtual lab software.


TINA is a powerful yet affordable circuit simulator for analog spice circuit simulation, digital and mixed circuit simulation

this may be what you want....i am not sure.....have a look. "Tina Pro - The Complete Electronics Lab Edison - Multimedia Lab for Exploring Electronics" ...   also CircuitMaker which you may know.

CircuitMaker Student Edition

Ssimulation program.... helpful for learning about circuits, testing designs or analyses, and even just drawing schematics for reports.


Monday, April 06, 2020

Cypress PSoC Mixed-Signal Array CY8C27x43

I am building the same using a PSoC( Programmable System on Chip). I will give a tiny snapshot from their site FYI. PSoC Mixed-Signal Array.

I had corresponded with you some time back when you had guided me to making a temperature controller .It was a very nice experience doing the same.

A true system-on-a-chip, PSoC devices are configurable mixed-signal arrays that integrate the microcontroller and related peripheral circuits typically found in an embedded design.

mail from TF

Programmable System-on-Chip - PSoC - CY8C27x43

The PSoC family consists of many Mixed-Signal Array with On-Chip Controller devices. These devices are designed to replace multiple traditional MCU-based system components with one, low cost single-chip programmable device. PSoC devices include configurable blocks of analog and digital logic, as well as programmable interconnects.

PSoC EvalPods

PSoC EvalPods are pods that connect to the ICE In-Circuit Emulator (CY3215-DK kit) to allow debugging capability.

CY3210 - CY8C27x43 PSoC(R) Evaluation Pod (EvalPod)

They can also function as a standalone device without debugging capability. The EvalPod has a 28-pin DIP footprint on the bottom for easy connection to development kits or other hardware.

Saturday, April 04, 2020

Interface 89C52 with 7135

i am interested in doing with 89C52. And now I trying to use AT89C52 and ICL 7135. And I use nterrupt 0 to get BCD data from ICL7135. I send you my program here and expect to get your advice soon.

post by NHT

I have made a circuit for you to study, also some idea about the code. you need to have Adobe Acrobat Reader

You can find it here Microcontroller you can now try to write the code and draw the circuit you need.

AT89C52 Parallel Interface to ICL7135

AT89C52 Parallel Interface to ICL7135

This circuit is an interface between 89C52 of Atmel with 7135 of Intersil.  With This circuit you can read analog data of both polarities you can change the range scale with extra circuits, you can store data on a EEPROM or send them to PC thru RS232 or Comm port.


Friday, February 21, 2020

What is a Relay - Jim Asks

(A text chat in Google talk long ago from my email records - 2007)

Jim: hello,
delabs: hello

Jim: i have a Small problem,it's about would u pls give me an information about relays,pls give different types of relays and their differences.

delabs: for what do you want to use the relay for.

What is a Relay - Jim Asks

Jim: Two door alarm settable for close or open door

delabs: there is a control signal and an output for relay, if you are using just a buzzer for alarm, no relay needed if you want to operate a big hooter or 230V lamp a relay is needed- or even a motor or solenoid to move some thing  Even a Solid State Relay can be used.

Bigger loads like large motors may need drives and containers. Some even have speed control. Big doors are more difficult to open and close. safety features needed.

The picture above shows also reed relays that are used for small signals - analog and telecom. In Solid State switching also we have small signal and power switches, using mosfet or triac.

Soldermans Basic Electronics: Relays and Contactors

Jim: let me check dis addr nd i'll get back 2 u just now.
Jim: ok but if i have a problem i'll get back 2 u,bye

Thursday, February 13, 2020

Soldering Iron Tip

Can I use stainless steel to replace a defective soldering iron tip?

mail from EA

Soldering iron tips are mostly alloys of copper. the thermal conductivity of steel is poor. buy a soldering iron tip available in the local market.

This image has a Tip for Soldering Iron and also has Soldering Iron Tips.

Soldering Iron Tip

Change Weller ET Series Soldering Tips

Changing the soldering tips on a PES51 pencil is very simple. You just have to make sure to take your time and don't force anything. Damaging your iron is not only possible, but easy when replacing the tips, so proceed with care.

Weller tips are magnetic and only original weller tips to be used.

The Basic Electronics Soldering & Desoldering Guide

The Basic Soldering Guide contains everything the beginner needs to solder electronics successfully, with guidance on choosing the right soldering iron, details of various solders and fluxes,


Thursday, February 06, 2020

Passive volume control

please if you don't mind I need to help to find a control circuit for volume of speaker 4 ohm or 8 ohm located in the another room far away of cassette or CD player by using only passive components with potentiometer without transformer.

mail from AD

i have attached to this mail a simple circuit you can build at home at low cost. This is the only alternative for the need that you have specified. it uses just a rotary switch and wire wound resistors.

Home Made Circuits

Volume control circuit for speaker 4 ohm or 8 ohm located in the another room far away. by using only passive components. This gives limited control and helps reduce volume when a conversation starts. The resistors are very low value.

Passive volume control with Potentiometer

A simple circuit you can build at home at low cost it uses just a rotary switch and wire wound resistors. Add more resistors and a rotary switch with more contacts for finer control.


Monday, January 13, 2020

Seven Segment LED display

how is the circuit for driving a seven segment led

mail from EA

A 7 segment LED display is used to display a number 0-9 using 7 LEDs, The circuit you design must have a BCD output, BCD means Binary coded decimal for number 0 it is 0000 and for number 9 it is 1001 see this chart i put in my site....  Electrical Tables

the BCD is fed to a BCD to 7 segment decoder like CD4511 or 7447 which has the logic to take care to drive your display, the displays are two types common anode and common cathode you have choose a driver to match your display, you will need to use current limiting resistors for every LED to limit current to 15mA or less. there are many circuits in my website which has examples of these.

Seven Segment LED display

you can also drive such displays with 7107 or 7135 to display analog signals, or with a microcontroller like 8051 using software decoding, even such examples and code is available at my website.Digital-Circuits. and Logic-Circuits.


I made an online tutorial for seven segment LED. Hope it helps you learn more.

Digital up down BCD counter "Simple Digital up down counter CD4029, with interactive javascript simulation." You can run the circuit online and try out without wiring it up.


Winding Transformers and Coils

i would need your help in designing transformers for rechargeable lamps. i really don't understand what the dots in front a coil stands for. all help (including pictures) would be really appreciated. my own just packed a few days ago and i would love to recoil the transformer.

mail from LA

You will have to do a lot of study in the internet, and experimentation too. Transformer winding is a specialized profession not a hobby at all. You can wind some coils or small signal transformers, that is ok. Please do not try to wind mains or 230/110 V transformers at home.

Winding Transformers

I can only give some tips, precautions and techniques to a winder. study these links....

Electrical Formulas, Calculations, Basic Electronics Engineering
I have put the link of a page but see all the pages of the website. The Dot polarity in a transformer stands for the direction of winding relative to each other. The Direction of winding could be clockwise or anti-clockwise.


NE612 - Balanced mixer with Local Oscillator

I am designing a circuit that implements an AM radio circuit that ultilises the IC Double mixer and Oscillator NE612. I was just wondering whether there is any standard symbol for this kind of IC.

mail from CM

There is no standard symbol for NE612, just a square box. You have to make a custom part in the CAD software or see if someone has done that. check these links on info of NE612 circuit and symbol....

GM47: Simple 30m Band QRP CW-Transceive 

The Rx mixer is followed by a IF stage featuring an NE592. The mixer's balanced output is directly connected to the amplifier's differential input, minimizing component count at this point.

Direct Conversion Receiver using NE612 for HF Bands

The NE612 is an integrated circuit which contains a balanced mixer with its own on-board local oscillator and voltage regulator. The mixer can provide up to 18dB of gain at 45 Mhz, and the local oscillator will operate up to 200 Mhz.

NE612 - Balanced mixer with Local Oscillator

HF Transceiver using NE612

 I would be working on the Transverter first, as with this, I could try out the 9Mhz SSB Module that I already have. I would be building the Transverter for the 14 Mhz band depending on the values from my DC Receiver project using the NE612 IC