delabs Circuits

Saturday, July 26, 2014

What is a Relay - Jim Asks

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

Jim: hello, anantha.
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

"A Relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays" - Wikipedia

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, July 24, 2014

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


Sunday, July 13, 2014

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.