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Latch Circuits
Latch Circuits:  #'s-K      L - Z

 

Last Updated: October 13, 2017 03:04 AM

Circuits Designed by Dave Johnson, P.E. :
Dusk To Dawn Latching Relay -  Over the years I have had to replace many dusk to dawn switches for outside lights.  These switches turn on a light during the night, then switch them off during daylight hours.  Some commercial switches are not sensitive enough to detect when the sun is out.  Others flutter badly during the dawn and dusk switching transitions, burning out compact fluorescent lamps, which do not like rapid power fluctuations. . . . Circuit by David Johnson P.E.-July, 2017

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

1-button lock provides high security -  03/04/99 EDN-Design ideas (contains several designs, scroll to find this one) Figure 1 is the block diagram of an easily programmed, single-button combination lock.  You operate the lock by using a series of short and long pulses from a momentary switch that masquerades as a doorbell button.  The circuit uses inexpensive CMOS logic.  The retriggerable timer, T1, locks out entries made after the T1 code-entry window, thereby greatly enhancing security.  The circuit in Figure 2 operates as follows: The Schmitt-trigger quad NAND gate, IC 1, debounces the code-entry switch and, with the aid of simple analog circuitry, produces separate outputs for activation times of less than and more than 0.3 sec.  These outputs connect to the select gate, IC 5 __ Circuit Design by Maxwell Strange, Fulton,MD

Add Latch-Off Current Limit to Regulator -  03/30/00 EDN Design Ideas:  in many applications, forcing a high-current power supply to latch off if a sustained fault condition exists can minimize the likelihood of damage to the pc-board traces and the power devices in the supply.  Pulse-width-modulation __ Circuit Design by Craig Varga, Linear Technology Corp, Milpitas, CA

Asynchronous Latches Safely -  04/28/94 EDN Design Ideas:  The circuit in Fig 1  is a digital latch that is resettable only after the condition that set the latch clears.  A set input (active low] permanently latches the output (active low].  A reset input (active high] resets the output to a logic high __ Circuit Design by Paul A Kemp, NASA Johnson Space Center, Houston, TX

Automatic latch-off saves batteries -  01/04/07  EDN Design Ideas:  Persistent latch prevents batteries from overdischarge __ Circuit Design by Kieran O'Malley, On Semiconductor, West Kingston, RI

Bipolars provide safe latch-off against opto failures -  12/07/00 EDN Design Ideas:  A typical SMPS (switch-mode power supply]uses a reference voltage and an optocoupler to regulate the output voltage.  The optocoupler carries the isolated information from the secondary side to the primary nonisolated side and ensures proper output regulation.  Current-modePDF contains multiple circuits, scroll to find this circuit.    __ Circuit Design by Christophe Basso, ON Semiconductor, Toulouse Cedex, France

Bistable Latch -  This is set-reset latch: it is a 'personality module for 4QD-TEC transistorised relay system.  However it is an R-S latch with a difference in that it can be set by a High or a Low signal (as appropriate) on either input.  The latch can be forced eithr way, and stays that way until next changed.   __ Designed by Richard Torrens

Bistable Switch -  This circuit shows how to implement a simple bistable (On/Off) switch.  You can also do this with a Schmitt trigger gate or inverter.  Just set R1 and R2 to bias  input to  center point of  Schmitt trigger’s hysteresis.   __ Designed by Andrew R. Morris

Circuit Adds Latch-Off Current Limit to Regulator -  03/30/00 EDN Design Ideas:  in many applications, forcing a high-current power supply to latch off if a sustained fault condition exists can minimize the likelihood of damage to the pc-board traces and the power devices in the supply.  Pulse-width-modulation __ Circuit Design by Craig Varga, Linear Technology Corp, Milpitas, CA

Circuit drives latching relays -  02/01/96 EDN Design Ideas:  Figure 1 shows a low-parts-count circuit that can drive one- or two-coil latching relays.  Latching relays are useful in sensitive analog designs.  The 74ACT174 hex flip-flop has ample capability to drive the Aromat TQ2E series of latching relays.  Both windings for the TQ2E-L2-5V two-coil relay are on the same magnetic element, so the windings' fields add.  You __ Circuit Design by Roy McCammon, 3M Austin, TX

Circuit Latches Solenoids at a Distance -  10/14/00 EDN Design Ideas:  The circuit in Figure 1 controls low-cost, latching solenoid valves over long distances.  For example, it can control one valve 1 km away using two wires and a 12V supply.  The circuit provide as 700 mA at 12V for the 20 msec necessary for latching a solenoid valve.  The CD4538 monostable multivibrator provide as an output-pulse width of 100 µsec to 1 sec.  The IC consumes 5-nA standby current.   __ Circuit Design by J Pelegri and D Ramirez, University of Valencia, Spain

Circuit prevents processor latch-up -  03/04/99 EDN Design Ideas:  Simple circuit prevents processor latch-up.  Dual one-shot makes rising- and falling-edge detector.  Simple circuit measures diesel's rotations per minute.  Fast, compact routine interfaces EEPROM to µC.  Photodetector sorts objects.  Single-button lock provide as high security.   __ Circuit Design by Michal Kobylecki and Wojda Wlodzimierz, MK Design, Warsaw, Poland

Circuits Drive Single-Coil Latching Relays -  13-Nov-08 EDN Design Ideas:  Five driver circuits operate single-coil latching relays __ Circuit Design by Alfredo H Saab and Tina Alikahi, Maxim Integrated Products, Sunnyvale, CA

CMOS Latches Relays -  11/18/10 EDN Design Ideas:  A driver circuit take pulses and sets relays.  [Design ideas - by JC Maillet, Gabriola island, BC Canada __ Circuit Design by JC Maillet, Gabriola Island, BC Canada

Continuity Tester Latching -  A continuity tester is a must on every service bench for testing cables, pc-boards, switches, motors, plugs, jacks, relays, and many other kinds of components.  But there are times when a simple continuity test (or your multi-meter) doesn't tell the whole story.  For example, vibration-induced problems in automobile wiring can be extremely difficult to detect because a short or open is not maintained long enough for a non-latching tester to respond __ Designed by Tony van Roon  VA3AVR

Drive a single coil latching relay without an H-bridge -  03/05/09  EDN Design Ideas:  Drive current in both directions to cut power consumption __ Circuit Design by Carlos Cossio, Santander, Spain

Drive latching relays -  02/01/96 EDN Design Ideas:  Figure 1 shows a low-parts-count circuit that can drive one- or two-coil latching relays.  Latching relays are useful in sensitive analog designs.  The 74ACT174 hex flip-flop has ample capability to drive the Aromat TQ2E series of latching relays.  Both windings for the TQ2E-L2-5V two-coil relay are on the same magnetic element, so the windings' fields add.  You __ Circuit Design by Roy McCammon, 3M Austin, TX

Drive Single-Coil Latching Relays -  11/13/08  EDN Design Ideas:  Five driver circuits operate single-coil latching relays __ Circuit Design by Alfredo H Saab and Tina Alikahi, Maxim Integrated Products, Sunnyvale, CA

Dusk To Dawn Latching Relay -  Over the years I have had to replace many dusk to dawn switches for outside lights.  These switches turn on a light during the night, then switch them off during daylight hours.  Some commercial switches are not sensitive enough to detect when the sun is out.  Others flutter badly during the dawn and dusk switching transitions, burning out compact fluorescent lamps, which do not like rapid power fluctuations. . . . Circuit by David Johnson P.E.-July, 2017

Electronic Relay Latching -  I've spent a lot of time thinking about how I want to wire my conversion.  The electrical system will consist of a combination of 12 volt DC, 24 volt DC, and 110 volt AC.  It's important that the system provide the greatest functionality, but have a simple interface.  It must be easy to install and relatively inexpensive to build.  The system can't be overly complicated and must be easy to maintain.   __ Designed by © 2001-2010 Craig Shepard

Fault-latch protects switchers -  02/19/04  EDN Design Ideas:  Many power-supply designers like to have a regulator latch off in the event of an overcurrent situation or other fault condition.  Yet, many PWM controllers do not internally support this latch-off function.  Most do, however, have a __ Circuit Design by Craig Varga, National Semiconductor, Phoenix, AZ

Forcible latch module -  This is set-reset latch: it is a 'personality module for 4QD-TEC transistorised relay system.  However it is an R-S latch with a difference in that it can be set by a High or a Low signal (as appropriate) on either input.  The latch can be forced eithr way, and stays that way until next changed.   __ Designed by Richard Torrens

Inverting latches make Simple Circuit VCO -  06/19/97 EDN Design Ideas:  The output frequency of the simple VCO in Figure 1, which is synthesized from inverting latch stages, is tunable to an integer multiple of the input frequency by selecting which output phases feed back to the input multiplexer.  The circuit __ Circuit Design by Ed Nielson, VLSI Technology, Sophia Antipolis, France


Latch Circuits:  #'s-K      L - Z

 


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