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Solid State Relay Circuits
#'s - R       S - Z



Last Updated: November 22, 2021 03:00 PM

Circuits Designed by Dave Johnson, P.E. :

Solid State Relay Requires Only 50ua Drive Current -  This circuit demands a control current that is 100 times smaller than that needed by a typical optically isolated solid state relays.  it is ideal for battery-powered systems.  Using a combination of a high current TRIAC and a very sensitive low current SCR. . . Circuit by Dave Johnson P.E.-June, 2000

Solid State Relay that is Bidirectional -  The circuit below can switch up to 4 amps of current with a peak voltage up to 20v.  it is fully isolated using two inexpensive red LEDs.  One LED forms a red light source, which illuminates a second red LED.  The circuit takes advantage of the 1.5v . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2009

Solid State Touch Activated Switch -  it does not get any easier if you want a solid state switch that is activated by the touch of a finger.  Two small metal pins route voltage through the finger skin to a MOSFET switch.  The circuit is great for situations where a membrane type mechanical switch . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

SSR Requires Ultra Low Control Current -  Most solid state relays require at least 5ma and often more input control current, to fully turn on the device.  But such current levels often force battery powered circuits to use excessively large batteries.  The relay hobby circuit shown below demands only 50uA of input current . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-778-8407




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

SCR phase control yields solid-state switch -  03/15/01 EDN Design Ideas:  SCRs (silicon-controlled rectifiers]/ PDF contains multiple circuits scroll to find the one of interest, or thyristors, have higher current and voltage ratings, lower conduction losses, and more robustness than TRIACs.  For these reasons, SCRs are better suited to high-power applications Design by James Keith

SCR Tester -  This simple SCR tester can be made with only a couple components.  it will provide a visual 'go' or 'no-go' indication--it is simply a voltage source, a lamp, and a resistor through which gate current is supplied.   __ Designed by Tony van Roon  VA3AVR

Semiconductor Relays -  general info and many example circuits __ Designed by Tomi Engdahl

Simple Circuit Electronic Breaker -  This circuit uses the on-resistance of the MOSFET as the current sensor.  Reset it by removing the input power or the load.  The circuit draws no current unless tripped.   __ Designed by Andrew R. Morris

Simple Circuit SSR has zero-cross on/off switching -  EDN Design Ideas:  02/16/2015    This AC solid-state relay enables zero-cross switching with quite a simple design.   This Design idea is a solid state relay (SSR) which uses a TRIAC to switch AC loads at high current.  There are plenty of simple SSR circuits available, but this may be the simplest circuit that achieves turn-on and turn-off only when the AC line voltage is near zero. Design by Dan Meeks

Simplify Solid-State Lighting Dimmer Design -  Solid-state lighting is rapidly becoming the most popular lighting option for a broad range of applications.  With the U.S.  government's mandate to save energy, incandescent lamps are being rendered largely obsolete, ...__ Electronics Projects for You

Solid State 120 VAC Lamp Chaser -  This circuit is basically the same as the 10 channel LED sequencer with the addition of solid state relays to control the AC lamps.  The relay shown in the diagram is a Radio Shack 3 amp unit (part no.275-310) that requires 1.2 volts DC to activate.  No current spec was given but I assume it needs just a few __ Designed by Bill Bowden

Solid State Auto Power-Off On Mains Failure -  A good number of circuits which turn off the power to the load on mains failure have already appeared in EFY.  This circuit is different because it consumes no power when...__ Electronics Projects for You

Solid state linear HF Amplifiers -  Not a project yet, but very theoretical thoughts about very practical amplifiers!  __ Designed by Manfred Mornhinweg

Solid State Power Controller -  The ckt is built around two 555 timer IC s. U1 and U2. U1 is wired as a variable duty cycle oscillator with a constant time period of around 0.1 second. Duty cycle can be varied from 0 to 100 per cent by R4 potentiometer. The output of U1 (pin 3) is connected to the rest input (pin 4) of U2. __ Designed by  Ravi Sumithraarachchi

Solid State Relay -  The basic function of a relay is to switch on power to a load using an electrically isolated, low-power control signal.  Hitherto, electromechanical relays have been the components of choice to...__ Electronics Projects for You

Solid State Relay -  Solid State Relays are available almost everywhere these days, however they remain very expensive.  Therefore, your efforts to build one yourself pays off.  Especially since it only needs a handful components and the circuitry is simple and straightforward __ Designed by Jan Hamer

Solid State Relay Requires Only 50ua Drive Current -  This circuit demands a control current that is 100 times smaller than that needed by a typical optically isolated solid state relays.  it is ideal for battery-powered systems.  Using a combination of a high current TRIAC and a very sensitive low current SCR. . . Circuit by Dave Johnson P.E.-June, 2000

Solid State Relay Space Heater Controller -  The space heater controller pictured above uses a 25 amp Solid State relay, a dual op-amp and a few other parts.  The circuit board was laid out on graph paper to work out locations for the holes.  The hole positions were then copied to a bread board to be used as a template for drilling the holes.  The bread board was then clamped on the top of the blank copper board as shown in the top picture and the marked holes were drilled using the bread board as a guide for the drill (no walking).  The drilled board was then sectioned into isolated islands using a Dremel tool and router bit as shown __ Designed by Bill Bowden

Solid state relay switch -  Solid State Relay Switch is a simple kit which will help you control (ON / OFF) a single high power circuit from a low power drive.  __ Designed by Rajkumar Sharma

Solid State Relay that is Bidirectional -  The circuit below can switch up to 4 amps of current with a peak voltage up to 20v.  it is fully isolated using two inexpensive red LEDs.  One LED forms a red light source, which illuminates a second red LED.  The circuit takes advantage of the 1.5v . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2009

Solid State Remote Control Switch -  Here is a solidstate remote control switch which uses readily available electronic components.  The control circuit comprises the transmitter and receiver sections.  The range of the transmitter is around seven metres.  The transmitter...__ Electronics Projects for You

Solid State Reversing -  This circuit uses solid state switching (transistors) to control direction of a DC motor.  You have precise control of the movement of the motor, and an indication of direction provided by LED's.   __ Designed by Andy Collison

Solid State Signal Lamp -  This solidstate signal lamp is a good alternative to revolving mechanical signaling lamps used in ambulances.  it uses ultra-bright blue LEDs for signaling.  However, you can replace blue LEDs with bright...__ Electronics Projects for You

Solid State Switch for DC-Operated Gadgets -  This solid state DC switch can be assembled using just three transistors and some passive components.  it can be used to switch on one gadget while switching off the second gadget __ Electronics Projects for You

Solid State Touch Activated Switch -  it does not get any easier if you want a solid state switch that is activated by the touch of a finger.  Two small metal pins route voltage through the finger skin to a MOSFET switch.  The circuit is great for situations where a membrane type mechanical switch . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Solid State Voltage Stabiliser -  in India, we have a large power distribution system with heavy distribution losses and variations in industrial/ domestic load.  This results in voltage variations that may damage electrical/ electronic appliances like...__ Electronics Projects for You

Solid-state analog data recorder runs for 7.4 days -  11/22/07  EDN Design Ideas:  Using a nonvolatile SRAM, this analog data recorder can store than seven days' worth of data Design by Vinay Kumar, Mysore, India

Solid-state breaker for microcontrollers -  10/29/13  EDN Design Ideas:  Electronically protect your load, driver, and microcontroller Design by Didier Juges

Solid-State Flasher Has Short-Circuit Protection -  01/16/97 EDN Design Ideas:  The circuit in Figure 1 switches an inductive or resistive grounded load using a bootstrapped, n-channel, power MOSFET.  The circuit features short-circuit, reverse-polarity, and transient-input-voltage-spike protection.  The input voltage, VDD, can vary from about 18 to 30V, and the circuit can handle as much as approximately 10A with proper heat sinking of the FET.  The circuit flashes at a rate of about 100 flashes/minute, with a duty cycle of about 47%.  You can use this circuit as a solid-state flasher for vehicles with 24V nominal-power systems. Design by Navdhish Gupta, TDF Corp, Naperville, IL

Solidstate Relay -  The basic function of a relay is to switch on power to a load using an electrically isolated, low-power control signal. Hitherto, electromechanical relays have been the components of choice to...__ Electronics Projects for You

Solid-State Relay Saves Battery's Life -  09/01/94 EDN Design Ideas:  The circuit in Fig 1 uses a low-resistance p-channel FET, Q4, to disconnect a load from the battery when the battery's voltage drops below a certain value.  After you disconnect the circuit, it remains off until you remove and replace the battery Design by Tom Gay, Siemens, Regensburg, Germany

Solid-state relays simplify Monitoring electric car battery-voltage -  02/19/04  EDN Design Ideas:  Figure 1 shows the propulsion system of an electric vehicle.  it includes an electric motor, drive electronics, a mechanical transmission, vehicle control/power management, a charging system, and a battery.  The long-term performance Design by Robert Krause, Fairchild Semiconductor, San Jose, CA

Solidstate Signal Lamp -  This solidstate signal lamp is a good alternative to revolving mechanical signaling lamps used in ambulances. it uses ultra-bright blue LEDs for signaling. However, you can replace blue LEDs with bright...__ 

Solidstate Switch For Dc-Operated Gadgets -  This solid state DC switch can be assembled using just three transistors and some passive components. it can be used to switch on one gadget while switching off the second gadget...__ 

Solid-State Tesla Coil, #1 -  Nikola Tesla is considered by some to be the greatest inventor of our modern electrical age, and many experts consider him to be the true father of radio.  However, today he is best remembered for his facsinating wireless power-transmission experiments, using his famous Tesla Coil.  The high-frequency air-core, oscillating Tesla Coil is just as exciting today as it was back in 1899 __ Designed by Tony van Roon  VA3AVR

Solid-State Tesla Coil, #2 -  Nikola Tesla is considered by some to be the greatest inventor of our modern electrical age, and many experts consider him to be the true father of radio.  However, today he is best remembered for his fascinating wireless power-transmission experiments, using his famous Tesla Coil.  The high-frequency air-core, oscillating Tesla Coil is just as exciting today as it was back in 1899 __ Designed by Tony van Roon  VA3AVR

Solid-State Two-Way Switch -  Two-way switches, more profoundly known as staircase switches, are widely used when a load has to be controlled from two ends of the location.  For example, a staircase lamp that needs...__ Electronics Projects for You

Square Tesla Coil -  Figure 1 shows the schematic diagram of the Tesla Coil circuit.  The circuit consists of little more than a few coils, a step-up power transformer, and a capacitor.  Power from an AC wall receptacle is fed to transformer T1 (a small neon-sign transformer) which steps the voltage up to about 3000-volts AC __ Designed by Tony van Roon  VA3AVR

SSR Requires Ultra Low Control Current -  Most solid state relays require at least 5ma and often more input control current, to fully turn on the device.  But such current levels often force battery powered circuits to use excessively large batteries.  The relay hobby circuit shown below demands only 50uA of input current . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

Switch intelligently controls current -  03/30/00 EDN Design Ideas:  This circuit can intelligently control ac or dc current when connected in series with a load.   PDF contains many circuits, please scroll to find this one Design by Jim Hartmann, Silent Knight LLC, Maple Grove, MN

Transformer driver controls bidirectional switch -  07/17/97 EDN Design Ideas:  You can use a transformer-driver IC to simply control a MOSFET on/off switch Design by Gerald Grady, Maxim Integrated Products, Sunnyvale, CA

Two Lead Solid-state Breaker Resets itself -  03/30/95 EDN Design Ideas:  Simple dc circuit breaker can protect a power supply from the ever-present screwdriver or even isolate a satellites dual power system from a short circuit in one subsystem Design by Phil Harvey, Technology Integration Inc, Bedford, MA

Ultra-Sensitive Solid State Clap Switch -  Here is the circuit of a highly sensitive clap switch that can be operated from a distance of up to 10 metres from the microphone.  Signals picked up by the microphone are amplified by transistors T1, T2, and T3.  Diode D1 detects clap signals and the resulting positive voltage is applied to the base of__ 

Got Designs?
Please eMail
if you want me to link to and/or post your original design Thanks.


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