EAC Electronics - Reed Relays, SMD, DIP, SIP, Tubular, Standard, and Custom

Technical Information
How to Use Relays in Electronic Circuits

(1) RELAY DRIVE

I₀ = Restoration current

When a signal is taken from the transistor which is used for driving the relay, and this signal is used for driving another circuit, even though the signal is intercepted by the transistor, a minute dark current flows to the relay. (I₀)
In the high sensitivity relays used for PC boards, the restoration level is very low, and there is the danger of improper restoration. For restoration, due to the dark current, the contact voltage drop and the reduction in resistance to vibration are of definite concern.

(2) RELAY DRIVE WITH EXTERNAL CONTACTS

relay with capacitor and resistor The relays used for PC boards are high sensitivity and fast response, and for this reason care must be taken when using external contacts for driving to provide proper protection from contact chatter and bounce.

When operation is infrequent, restoration delay time by means of a condenser can be used to absorb the effect of bounce and chatter, (However, a capacitor only is ineffective; a resistor should be connected as shown.)

(3) DRIVING ELECTRONIC CIRCUITS BY MEANS OF RELAY

3-1 Electronic chatterless circuit
Even though there are relays having a specific characteristic of chatterless operation and to that extent are used in ordinary electrical circuits wherever possible, in the same manner as mercury relays in binary counter circuits, the input absolutely demands a chatterless operation. To accomplish this, an electric chatterless circuit must be used since chattering is not totally permissible.

Notes.

The line to A, B, and C must be as short as possible.
Because noise from the coil section can be induced in the contact section, care must be taken.

Even if chattering develops only on one side of the NO and NC contact arrangement, the flip-flop circuit sends a signal to the counter without a miss.
(However, bouncing extending from both NO and NC sides to the opposite contact side must be absolutely avoided.)

3-2 Triac drive
In using electronic circuits for direct triac drive, because the electronic and power circuits are not totally isolated from each other, erroneous operation and damage can easily occur. Driving by means of a relay is most economical and is effective as well. (In case of photocoupling and pulse transformers using, the circuit becomes complicated.)

When zero-cross switching is a required characteristic, use a SSR (solid state relay).

Contents

		Relay Selector Chart
		Glossary
		Ripple Factor
		Kinds of Load
		Contact Protection Circuits

		Relays in Electronic Circuits
		Know-how of Circuit Design
		Mounting Direction for Relays
		Soldering and Cleaning Recommendations
		Representative Latching Relay Circuits

Standard Terms:	Check/Money Order Net 30 Credit Card
Minimum Order:	$100.00

Wholesale/OEM

Distributed by
CeeJay

16475 Canyon Hills Road #3

Chino Hills, California 91709
Tel: (714) 572-2169

Fax: (714) 572-2169

E-mail: sales@ceejay.com