Friday, August 18, 2017

LM555 Voltage Doubler

This circuit shows the voltage doubler working with a 555. LM555 has good drive 200mA, both Vcc and Gnd.

LM555 Voltage Doubler

555 has the advantage of having a high drive as well as being a Mixed Design, Analog Programmable chip.That may be a High Title for such humble a chip.

Power Electronic Circuits 

It has the capability of a Mini ADC due to its VCO function. It could form even a simple switching supply. Power Line Modems have been designed using this chip.

Timers, Modulators, Trip Relays and even a Timer for The Humble Bread Toaster. Musical circuits, Piano and Metronome Galore, it drives Speakers directly.

The Star of what we used to Know as Chip as IC. Too small today in the days of ASIC and FPGA. But ideal for Education of Electronics and Simple Real times Solutions.

Tuesday, August 15, 2017

Voltage to Frequency Converter ICL8038

This was a small circuit made for driving an Impact counter. The heart being ICL8038. It must have been a Motor driving a Conveyor, the motor has a feedback attachment called Tachogenerator.

Tacho Counter for Speed and Quantity Measurement


Voltage to Frequency Converter ICL8038

Only part of the circuit is shown here. See the image of product here Tacho Counter. The configuration is derived from the Application Notes of Intersil. The Voltage from Tachogenerator is Measured on a DPM-DVM and also fed to this circuit after attenuation and filtering.

Anwheel.com – Industrial Automation and Process Control

The square pulses of 8038 is used to derive a Logic pulse train for a CD4040. The CD4040 works of 0 and 12V. The above circuit is on +12 and -12. That is the reason R10-R15-Q1 are used. The pulses are 0-12V pulses. The Zero is Virtual like the Virtual Ground in low current power supplies.

Wednesday, August 09, 2017

+5 to -5 using a 555 Astable Multivibrator

This is a very simple -5V supply using one 555, useful for analog blocks using FET Opamps using low power. This circuit came up when i had to design limited by inventory. It worked well for its need. It converts Positive Five Volts to Negative Five Volts to create a dual supply.

+5 to -5 using a 555 Astable Multivibrator

This +5 to -5 using a 555 Astable Multivibrator.is not a high efficiency design, in fact it cannot take a heavy load. Circuits having some CMOS Opamps and a A/D convertor is ok. Even very small battery designs must avoid this circuit.

Home Made Circuits

This suits well when you want to power an analog amp which has to measure voltages which swing on either sides of zero. It can be used in a LCD based portable measuring instrument running on a rechargeable 9V battery.

Powering a strain gauge amp may be one use, another may be like a RTD temperature meter for -50 to +150 deg C.

Tuesday, July 11, 2017

Normally Closed AC SSR

This is a Normally Closed PCB Mount SSR. That means when DC Control input is low, the triac is ON, the output passes the load current to turn on small heater-motor-lamp or a bigger contacter-drive etc.

NC AC Load SSR DC control

NC Solid State Relay or SSR

When input DC is high the output is OFF. This is also Optically Isolated from Mains. A Microcontroller output which is buffered by some driver can drive this relay. It is better that in big systems these SSR Modules can be on another PCB, to avoid mains wiring near Logic circuits. But this cannot be used for medical electronics, or critical applications. More reliability and visual isolation of voltages may be required for such equipment.

Tuesday, July 04, 2017

RTD Pt-100 Four Point Alarm

Here 4052 is used as an analog multiplexer, U3A TL062 opamp is wired as a 1mA Constant Current Source. It pumps 1mA into U2 4052 pin 13 X . Depending on BCD code on inputs A, B of 4052 the current is routed to any one of the four RTD 100E, whose one end is connected to X0-X3. The current then flows to GND thru the Platinum 100E resistance. The Y0-Y3 monitors the mV developed on RTD in tandem with X0-X3 positions. Like a ganged rotary switch. The Output mV at Y is the mV of Active Channel as selected by the BCD of 4029.

RTD Pt-100 Four Point Alarm - del90001

The BCD is provided by 4029 counter which is clocked by a 555. U5A cancels out the 100E mV (1mA * 100E) of a cold RTD and Amplifies the differential mV. This output of U5A is in proportion with measured temperature. U5B compares the mV that was obtained with a preset mV of POT1, which is a user setting called setpoint. The difference is amplified by U5B which is saturated by U3B comparator which adds a little hysteresis too. R7-C2 further dampen and slow the response. This finally drives Q2 to provide a Logic Signal indicating if temperature is below or above setpoint.

RTD Pt-100 Four Point Alarm

Four points in a Closed Loop Temperature Control System is Monitored and a Alarm set to go off when the temperature goes beyond the set limit.

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