Thursday, December 14, 2017

DC-DC SSR Solid State Relay

This is a DC Input DC Output SSR Solid State Relay. It was made for Printing or Photo Processing Equipment. It has an optical isolation and can be used for inductive loads.

DC-DC SSR Solid State Relay

The R1 Limits current and Z1 and D1 protects. The 2N3904 limits current in the Opto-Led. When the LED in CNY17-3 turns on, the Light passes thru a electrically insulating area and falls on the photo-transistor in the opto-coupler. This transistor conducts biasing Q2 PNP power transistor.

DC Load DC Control SSR

Then Q2 drives Q3 to saturation, turning it on. Q3 is a High-Voltage and High-Power rugged device. This can derive a solenoid, DC motor or Lamp.

Tuesday, December 12, 2017

Multiplexed Presettable Timer with ICM7217

This was a attempt to make a Sequential Timer with ICM7217 of Intersil, even though it worked well, it was not developed beyond the prototype stage or first iteration. Only when a product is made in some numbers, the documentation and designs become clear, streamlined and seasoned.


The PCB and Circuit are not complete. It may give ideas. During this time, as far as i can remember, these were the only large CMOS devices. 8080-85 and Z80 devices consumed lot of power and needed big boards and supplies.

ICM7217 4-Digit, Presettable, LED Up/Down Counter Maxim


Study this, if you are not good at firmware or you need a simple solution, this is still a versatile chip. It is better you make your own PCB. This board can be used for prototyping only.

Timer Circuit pdf
Clock Circuit pdf

The MM5369AA and 3.579545 MHz
I have converted from DOS Orcad to Windows, corrected some mistakes, use with care. Orcad on DOS had a very user friendly interface, it had a near windows like GUI on DOS, when windows did not even exist, It had right mouse button controls too.

Saturday, December 02, 2017

Connection Diagram of AC Control SSR

SSR or Solid State Relay or Electronic Relay Connection Method. This is a Thyristor Based Normally Open 230V Switch that can be turned on / off at a fast rate. This switches at Zero Crossover .Built In Snubber reduces EMI and protects the SSR. USE SAME PHASE FOR I/P & O/P.

AC-AC-SSR Solid State Relay


AC-AC SSR Wiring
  • No moving parts hence no wear and tear.
  • Dissipates Heat when in On Condition.
  • Use adequate Heat Sink or SSR will fail. ( 10g / Amp)
  • Dissipation is 1.5 Watts per Amp thru Load.
  • Input to Output is optically isolated 2kV.
  • This one is AC 230V Control AC 230V N.O. Output.
  • Off state snubber Leakage is around 5 mA.
Notes -

The Termination's of High Current Lines going to Load must be very tight and crimped. Loose contacts will Spark and cause Fire. Fuse Rating of HRC Fuse - High Rupture Capacity (HRC) Fuse is Safe and Reliable. 5kW Heater at 230V is 5,000 / 230 in Amps of Fuse Rating.

Circuits by Application

Analog Circuits

  1. Battery Level Indicator
  2. Simple Sample and Hold
  3. Sample and Hold Standby
  4. Voltmeter Attenuator
  5. Precision Current Source
  6. Opamp Supply Virtual Ground

SCR and Triac

  1. Solid State Relay
  2. Normally Closed AC SSR
  3. AC-AC-SSR
  4. DC-DC SSR
  5. 2N2646 based Pulser
  6. Drive SCR thyristor

Mains Power

  1. Flashing Neon Lamp
  2. Dimmer power control
  3. Edison Bulb Life Extend
  4. Mains Current LED
  5. Mains Voltage LED

Digital Circuits

  1. Simple Digital Counter
  2. Running Lights
  3. Frequency Divider
  4. Crystal Oscillator
  5. Simple High speed switch
  6. Differential TTL converter

Measureall DMM

  1. Ohmmeter Measure Resistance
  2. Precision Digital Attenuator
  3. Precision Amplifier

Mixed Circuits

  1. Monostable Multivibrator
  2. Digital to Analog
  3. LM311 Oscillator
  4. PLL using 4046
  5. VCO with LM331
  6. BCD Thumbwheel to Analog
  7. V to F Converter ICL8038
555 Circuits
  1. OR gate with two 555
  2. fixed frequency duty cycle
  3. Pulse width modulation
  4. Astable Multivibrator
  5. uC Reset Generator
  6. LM555 Voltage Doubler
  7. 555 Power Oscillator
Discrete Circuits
  1. Isolated dual supply
  2. Sound to light converter
  3. Water operated relay
  4. Telephone Indicator
  5. Passive volume control
  6. RS232 Opto-Isolation
  7. Voltage Level Indicator
  8. Relay Driver
  9. Constant Current LED
  10. Voltage Doubler
  11. FET Current Source
Opamp Circuits
  1. Three Opamp Differential
  2. Two Opamp Differential
  3. Buffer Opamps
  4. Differential Op-Amp
  5. Inverting Opamp
  6. Non Inverting Opamp
  7. Digital gain control
  8. Square Triangle Oscillator
  9. Dual Polarity Output Amps
  10. Ammeter Precision Rectifier
  11. Voltage / Current 4-20 mA
  12. Current Source for RTD
Power Electronics
  1. Dual Power Supply
  2. Single Power Supply
  3. Battery Backup Supply
  4. 5V 1A Supply LM2575
  5. 5V Power Supply L296
  6. Dual Power Supply
  7. Tubelight Electronic Choke
  8. Voltage Doublers Multipliers
  9. White LED Lamp on Ni-Cd

uC and uP

  1. PC RS232 with MAX232A
  2. Battery Backup SRAM
  3. watchdog uC uP systems
Instrumentation Circuits
  1. Mains monitor LM3914
  2. Simple Mains monitor
  3. single digit voltmeter
  4. High Resistance Meter
  5. Diode Thermometer
  6. Function Generator
  7. Diode Leakage Tester
  8. Analog LED Ohm Meter
  9. Millivolt Source Current Loop
Process Control
  1. AD590 - temperature
  2. Thermocouple Amplifier
  3. Linearizing Thermocouple
  4. Thermocouple Amplifier
  5. 0-1V to 4-20 mA
  6. 1-5V to 4-20 mA
  7. InfraRed - Optical Switch
  8. InfraRed Detector

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