Kerry Wong writes:
Latching relay (a.k.a. impulse relay) can be turned on and off by momentarily applying a voltage across the relay coil. The relay would maintain in its last switched state without the need to maintain the coil current. In this post, I will show a simple circuit which can be used to drive such relays. In the video towards the end, I also included more explanations and some demonstrations.
The relay I am using here is a latching RF relay. It is used to switch the input signal between its two outputs. For this particular relay, the input has an APC-7 connector. One side of the output has an N connector and the other side is 50 Ohm terminated. Although this relay is an RF relay, the method I described below is applicable to any latching relays.
Many dedicated ICs (such as MAX4820, MAX4821) can be used for driving such relays. Because of nature of the latching relay, no H-bridge is needed (although you can definitely use an H-bridge, but it would be wasteful).
How to drive a latching relay - [Link]
Despite a low power consumption this relay handles 5A/250VAC while maintaining a considerably long lifetime.
If we should mark an electronic component by a term “sympathic”, then the FTR-MY MY relay should be one of adepts …. Why? It´s simply chic. FTR-MY is:
- slim (5mm), so it doesn´t take much time on a PCB (only 100 mm2)
- relatively low profile (12mm), so it´s usable in majority of applications
- very sensitive (110 mW), operates even at 54 mW
- handles 5A/250VAC but thanks to bifurcated gold-plated contacts doesn´t have problems neither with small signals
- outstands by long mechanical and electrical lifetime
In praxis it looks so, that on a small PCB space, where we´d usually fit 3 common relays, it´s possible to assemble 10 pcs FTR-MY.
Despite small dimensions FTR-MY has an isolation strength of 3000VAC. Even thanks to a low power consumption, max. operating temperature is +90°C and at the same time FTR-MY enables dense assembly without worry about overheating.
The last bonus of FTR-MY is a considerably affordable price. By its specification, this series is comparable (or even better) with series NY.
Slim, humble and long-age – this is the Fujitsu FTR-MY relay - [Link]
by w2aew @ youtube.com:
Today’s “Back to Basics” tutorial topic – why flyback or snubber diodes are used around relay coils when switched or controlled by low power electronics. We’ll talk about how and why dangerously high voltages can be generated from the collapse of the stored magnetic energy in the coil when they’re switched off, and how the diode can protect the low power electronics from being damaged by these high voltages. Some voltage and current measurements are made on an actual circuit to see the real-world effects.
Why diodes are used around relay coils - [Link]
This project is an one Channel Relay Driver suitable for a variety of projects. Check specifications on the page below.
One Channel Relay Driver - [Link]
8 Channel Relay Board is a simple and convenient way to interface 8 relays for switching application in your project. Input voltage level support TTL as well as CMOS. Easy interface with Microcontrollers based projects and analog circuits.
8 Channel Relay Board - [Link]
You are planning to use Arduino in your project but you need some kind of remote control functionality. A standalone Arduino won’t provide what you need but this DIY shield may be a good solution for you. It includes a 433.92Mhz RF receiver which lets you send commands to Arduino wirelessly and four SPDT relays which can be used for switching purposes.
Each relay is capable of switching up to 10A @ 250VAC so they can be used to control mains powered devices. There are four LEDS indicating the status of the relays. The terminal blocks on the shield lets you easily connect the devices you will control.
The RF receiver is a module that can be found in the market easily. It is directly soldered to the shield and runs at 4800bps. The board has an antenna input which lets you solder your custom antenna to increase the wireless range.
DIY 433MHz RF Receiver and 4 x SPDT Relay Shield - [Link]
Remote control your electrical devices through your local network or internet. The circuit contains one output (Relay) and one input (isolated input). The whole project was built by using arduino nano platform and an ENC28J60 ethernet module. It can be used the W5100 ethernet module instead of ENC28J60, by replacing the UIPEthernet library to Ethernet library.
Moreover, the control is made from the Android application I wrote and it’s available on Google Play (https://play.google.com/store/apps/details?id=com.serasidis.NetworkRelay).
The schematic diagram, arduino sketch, photos and demonstration video is on my web site:
Arduino Network relay - [Link]
To tell the truth, probably no, but we have for you a few hints for relays which are very close to an ideal.
Signal relay is almost an „ideal component“ thanks to a practically zero distortion and a total isolation of a switched signal from a control one. That is naturally one of the main features of all electromechanical relays, but at signal relays it´s especially valued, as we usually require switching of relatively small signals. Favorite and widely used are for example relays Fujitsu series B3 and B4 (miniature SMT and THT relays) and series AxW (miniature only 5mm high relay) – all with bifurcated gold-plated contacts for a high reliability.
A novelty in our portfolio is the series Fujitsu NA representing something like a “golden middle way “. With dimensions 7,4×14,9×9,7 mm it belongs to narrow miniature relay enabling a high density of components on a PCB. Even though relay NA is somewhat bigger than for example series B4, but it´s able to withstand higher AC current – up to 0.5A/125VAC (vs. 0.3A at series B4) and it also provides an extreme mechanical lifetime up to 100×106 , what´s approximately twice that of B4 series. Sensitive coils, with a consumption of 0.1-0.3W at majority of types enable a dense mounting without problems with overheating.
From the point of view of the lowest possible consumption are naturally the best latching relays (with a permanent magnet) controlled only by pulses. Usually they´re easy to recognize by a letter „L“ behind the series marking (for example NAL, JSL). In a Fujitsu signal relays overview and the Fujitsu catalogue can be easily found a comparison among particular types as well as detailed information about them. We try to keep the most favorite types always on stock, what´s also reflected in the substantial increasing of stock.
Does a universal signal relay exist? - [Link]
This is a 8 channel relay interface board using ULN2803. All the relays are opto-isolated using optocouplers and can be controlled directly using a microcontroller of any kind (Arduino , 8051, AVR, PIC, DSP, ARM, MSP430, TTL logic) or a PC.
It’s easy to manufacture and have three pin screw terminals for easy connectivity.
8 Opto-isolated Relay board - [Link]
by Viktor Safronov:
Sometimes you may need a group of switches where, if any switch is activated, it deactivates the previously active switch. This Design Idea implements such a function with relays.
This “one and only one” function is often implemented as mechanical switches in which an actuator (usually a movable metal bracket) is used to switch contact groups on and off. When any switch is pressed, this bracket first deactivates all switches, then activates the pressed switch.
Exclusively select 1 of N relays - [Link]