Switches in Electronics

Switches are electromechanical devices. The are used to control the  path of current or energy flow. Power switches are used to turn on and off loads. The contacts should be robust and have immunity to  sparking and corrosion. Switches for signals need to be gold plated for low contact resistance and within a sealed enclosure.

Switches in Electronics

A Neon bulb should have a resistor is series to make a Neon Lamp. All specs in designer viewpoint.

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Electronic Product Design

Electronic Product Design involves Electrical, Mechanical and Material Engineering too. This depends on the product complexity and the involvement of the R&D team in the component engineering too. Some products like RF and Robotics may need custom semiconductors and Some Wearable Electronics may need a custom ASIC as the heart of the device. 

Circuit Design Service of delabs  - Product and Circuit design. Consulting tech service.

delabs design service

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SoC the System on Chip and IP

When a product has to be made small, the board real estate is limited or it has to be manufactured in large numbers.... SoC is the Answer. A Microprocessor evolved into a Microcontroller by packing many external chips into one chip. Now uC Card along with the other blocks like A-D, Port Drivers, Networking elements, Display Driver and other peripherals can be packed into one chip.

Some Power Supply and RF blocks cannot be easily added inside as they have a silicon processing more specific to their applications. Laser trimmed Instrumentation Op-Amps, high accuracy resistor arrays, high value capacitors, magnetics and supporting chips are placed outside on the PCB.

The SOC can pack Digital Chips, Memory, A/D, D/A converters, uC, RAM and Custom programmable areas. For more specialized communications, analog and power requirements; Special SoC types can tackle RF and Power management within a chip because of proprietary silicon processing expertise.

System-on-Chip SoC and IP

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MC7800 MC7900 1 Amp Voltage Regulators

These voltage regulators are monolithic integrated circuits designed as fixed−voltage regulators for a wide variety of applications including local, on−card regulation. These regulators employ internal current limiting, thermal shutdown, and safe−area compensation.

Linear Voltage Regulators - On Semiconductor 

With adequate heatsinking they can deliver output currents in excess of 1.0 A. Although designed primarily as a fixed voltage regulator, these devices can be used with external components to obtain adjustable voltages and current

MC7800 - Voltage Regulators 1A - On Semiconductor

Standard Voltages are - 5V - 6V - 8V - 9V - 12V - 15V - 18V - 24V

MC7900 - Voltage Regulators 1A - On Semiconductor

The MC7900 series of fixed output negative voltage regulators are intended as complements to the popular MC7800 series devices. These negative regulators are available in the same seven voltage options as the MC7800 devices.

Common ground is required between the input and the output voltages. The input  voltage must remain typically 2.0 V above more negative even during the high point of the input ripple voltage.

Current Boost Regulator - Postive

Current Regulator

Short Circuit Protection


Adjusrtable Voltage Regulator


All above circuits can be adapted to the negative 7900 regulators circuits. You have to remember PNP transistors are not used in the final output stages. NPN can take the heat and current loads. So it makes your Negative Regulator Boosters a bit complex.  The below two circuits have the 7900 regulators playing their negative roles.


Current Boost Regulator - Negative|

When a boost transistor is used, short circuit currents are equal to the sum of the series pass and regulator limits, which are measured at 3.2 A and 1.8 A respectively in this case. Series pass limiting is approximately equal to 0.6 V/RSC. Operation beyond this point to the peak current capability of the MC7905C is possible if the regulator is mounted on a heatsink; otherwise thermal shutdown will occur when the additional load current is picked up by the regulator.


Opamp Dual 15V Supply

The MC7815 and MC7915 positive and negative regulators may be connected as shown to obtain a dual power supply for operational amplifiers. A clamp diode should be used at the output of the MC7815 to prevent potential latch−up problems whenever the output of the positive regulator (MC7815) is drawn below ground with an
output current greater than 200 mA.

Accelerometers and Gyroscopes

The ADXL345 from Analog Devices is a small, thin, low power, 3-axis accelerometer with high resolution 13-bit measurement at up to ±16 g.

Ben's HobbyCorner - Software - Bascom-examples On the right the ADXL345, connected to the I2c-bus, and when connected well, you will find it in the I2c-scanner. This is the Bascom-AVR code for the I2c-scanner. When the ADXL345 and the HMC5843 are fixed on the board you should see this in Hyperterminal.

Bascom and ADXL345

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Power Quality and Clean Energy

"Earth leakage currents arise mainly from the EMC filters built into electronic equipment with switched mode power supplies. Standards limit the leakage current from non-fixed equipment (i.e. equipment that plugs into a standard socket outlet) to less than 3.5 mA. When a lot of electronic equipment is in use, the total leakage current in the protective conductor can become significant."

Earthing Practice by Trevor Charlton

Clean Power

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Function Generator using the CA3140

Here is a complete project which will help in learning to apply the CA3140 in a small instrument that could be used in your test bench along with the oscilloscope. It is necessary to study the datasheet for understanding the device and this application with full details.    

CA3140 4.5MHz, BiMOS Operational Amplifier with MOSFET Input/Bipolar Output

"A function generator having a wide tuning range is shown in Figure 10. The 1,000,000/1 adjustment range is accomplished by a single variable potentiometer or by an auxiliary sweeping signal. The CA3140 functions as a non-inverting readout amplifier of the triangular signal developed across the integrating capacitor network connected to the output of the CA3080A current source."

Function Generator Block Diagram

Meter Driver and Buffer Amplifier

Figure 11 shows the CA3140 connected as a meter driver and buffer amplifier. Low driving impedance is required of the CA3080A current source to assure smooth operation of the Frequency Adjustment Control. This low-driving impedance requirement is easily met by using a CA3140 connected as a voltage follower. Moreover, a meter may be placed across the input to the CA3080A to give a logarithmic analog indication of the function generator’s frequency.

Meter Buffer and Sine Shaper

 Sine Wave Shaper

The circuit shown in Figure 12 uses a CA3140 as a voltage follower in combination with diodes from the CA3019 Array to convert the triangular signal from the function generator to a sine-wave output signal having typically less than 2% THD.

Function Generator

Triangle and Square Wave Generation

Buffered triangular output signals are then applied to a second CA3080 functioning as a high speed hysteresis switch. Output from the switch is returned directly back to the input of the CA3080A current source, thereby, completing the positive feedback loop

The triangular output level is determined by the four 1N914 level limiting diodes of the second CA3080 and the resistor divider network connected to Terminal No. 2 (input) of the CA3080. These diodes establish the input trip level to this switching stage and, therefore, indirectly determine the amplitude of the output triangle.

Sweep Generator

Sweeping Generator

Figure 13 shows a sweeping generator. Three CA3140s are used in this circuit. One CA3140 is used as an integrator, a second device is used as a hysteresis switch that determines the starting and stopping points of the sweep. A third CA3140 is used as a logarithmic shaping network for the log function. Rates and slopes, as well as sawtooth, triangle, and logarithmic sweeps are generated by this circuit.

Wideband Amp
Wideband Output Amplifier

Figure 14 shows a high slew rate, wideband amplifier suitable for use as a 50Ω transmission line driver. This circuit, when used in conjunction with the function generator
and sine wave shaper circuits shown in Figures 10 and 12 provides 18VP-P output open circuited, or 9VP-P output when terminated in 50Ω. The slew rate required of this
amplifier is 28V/μs (18VP-P x π x 0.5MHz).

Power Supply for Project

Use a good step-down transformer to isolate the mains supply and reduce the AC voltage. Rectify with a diode bridge to get DC, filter the DC with large electrolytic capacitors. Then implement this Dual Power Supply circuit along with LM7815 and LM7915  - Dual Polarity Power Supply

Most of my early life as a R&D Engineer, i have been in Analog. Here are design aspects of circuits using Op-amps and Comparators. Discrete Semiconductor Circuit design like using Transistors and Diodes. RLC parts. The related blog is my delabs Schematics.

Analog Design

Things related to Electronic Design in all its aspects. That includes the prototyping, mechanical, electrical and PCB. Product Safety, EMI-RFI, Reliability and Robustness. The related blog is here Design Gopher

Electronic Design

This Section is related to Microcontrollers and Related Resources. Microcontroller, SOC, FPGA, ASIC. From 80C31 to the Latest ARM chips will be the scope of this section.  The related blog is  here Hyper Embedded

Embedded Systems

Product Design - Industrial Automation and Instrumentation. delabs Technologies uses the brand names delabs and dapj in its Web Services and Resource Sites. These together form an Electronics Informatics and Product Design Technologies Web Consultatory. Updates are Here delabs SmartView

delabs Synergy Car

The design of Power Supplies, DC to DC and AC to DC Convertors, SMPS, High Voltage and High Current equipment. Mosfets, Thyristor, Schottky Diodes, Ferrite Magnetics and Chokes are the various components used. Power Electronics qt delabs.

 Power Electronics


Electronic Components and Engineering Materials. The parts, kits, tools that are used in designing and manufacturing electronic products. The Mechanical Nuts-Bolts and Raw Materials used in Electronic Manufacturing. The related blog - Components and Materials.

Electronic Components delabs