Circuits FAQ

This is the Archive of Electronics & Technologies related Question & Answers. Ask Questions at EE BBS FAQ. To get a project designed by delabs visit Design Service.

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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.