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Monday, January 28, 2019

SSR Solid State Relay DC Control

This is the newer version of NO - Normally Open DC Control SSR. It has a Constant current source that is more stable and robust.

You could use it to control AC powered Electricals like Heaters, Motors and Fans. It can also be used to Switch ON and OFF any Equipment, Control Panel or System.

SSR Solid State Relay NO New

You have to choose the correct current rating and heatsink needs of Triac. This is the older version below. It has a shunt current control. This new circuit above has a regulated current source.

DC-AC Solid State Relay or SSR - del30008

This is a basic output Module in control systems. It is faster than Electromagnetic relays but has some heating in the triac. Some designs with mosfets are also available. SSR with a IGBT - Insulated Gate Bipolar Transistors also can be made for large powers.

Thursday, January 24, 2019

Generic LM317 Switching Supply

This was a common way LM317 was used to get a stable power for small devices. It is still useful for learning and some blocks of the circuit are still used today in modern industrial systems.

Generic LM317 Switching Supply

Before the SMPS took over as the default DC source in most systems; designers would use switchers to reduce thermal losses in Linear Supplies.

Linear Supplies have practically no noise or EMI_RFI (generation) issues . It is clean but not green. The efficiency is low. Transformer loss, heat loss in devices. The Product Safety is very high; but you need to use a Toroidal or Split-Bobbin Transformer for better isolation.

Power Electronic Circuits

The cost of these supplies are high as more copper is used, the space and weight is also considerable. Reliability and long term stability is excellent in these systems.

Dual Supply +5 and -5 using 555

In this circuit the 12 DC, two wire is converted to three wire +5 and 0 and -5 dual supply useful for op-amps or other interface circuits. You could use 7805 and 7905 low current TO92 package.

Dual Supply +5 and -5 using 555

Regulated supply is essential for precision analog circuits.  This also could be used for signal conditioners that are built into the sensors. They are called voltage or current transmitters.

Negative supply also ensures total off or high-z in cmos analog switching. If you have crosstalk or leakage error in the Analog Mux; use a dual supply FET switches to turn total off and total on.

Instrumentation and Measurement Circuits

Datel (ge) mux chips had low on and off, but were expensive. Some cmos switches can improve with dual supply, but care to be taken that the negative voltage does not reach the ADC or uC stages.