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2N2646 based Voltage controlled SCR Pulser
Written by delabs   
Tuesday, 23 November 2010 00:00

A Center tap 50Hz Step Down Transformer with two diodes is used to get a train of Positive Sine Pulses at 100Hz which is applied to Q6 base via R51. 2N2646 is a unijunction transistor(UJT) in a TO-18 metal package. The control voltage or voltage proportional to error is fed to R56-Q3, The UJT drives a pulse transformer which provides isolation from the Load which the SCR bridge is controlling. This phase angle control gives a near Linear closed loop control for a SCR bridge which may be used in...

This post is a snippet, to see the full content visit this blog or http://www.dapj.net/. The blogs are listed at dapj Web.

imageA Center tap 50Hz Step Down Transformer with two diodes is used to get a train of Positive Sine Pulses at 100Hz which is applied to Q6 base via R51. 2N2646 is a unijunction transistor(UJT) in a TO-18 metal package. The control voltage or voltage proportional to error is fed to R56-Q3, The UJT drives a pulse transformer which provides isolation from the Load which the SCR bridge is controlling. This phase angle control gives a near Linear closed loop control for a SCR bridge which may be used in Electroplating or a Preregulator of a big power supply.

2N2646 based Voltage controlled SCR Pulser

Read more: http://feedproxy.google.com/~r/SchematicsOfDelabs/~3/0qoJQZAngGM/2n2646-based-voltage-controlled-scr.html

Last Updated on Tuesday, 23 November 2010 14:12
 
DC-DC SSR Solid State Relay
Written by delabs   
Tuesday, 16 November 2010 00:00

 

 

 

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. 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. Then Q2 drives Q3 to saturation,...

This post is a snippet, to see the full content visit this blog or http://www.dapj.net/. The blogs are listed at dapj Web.

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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 SSR

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. 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.

Read more: http://feedproxy.google.com/~r/SchematicsOfDelabs/~3/I83ualhM_UE/dc-dc-ssr-solid-state-relay.html

Last Updated on Tuesday, 16 November 2010 14:32
 
Basic Design of an Electronic Load
Written by admin   
Thursday, 04 November 2010 04:00

Electronic Loads are devices which may be used to test a great variety of electronic designs. Generally speaking, electronic loads are devices which may be configured to act as artificial loads, sinking a preset current.

Basic Design of an Electronic Load –[Part1][Part2]

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Last Updated on Thursday, 04 November 2010 14:20
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Square and Triangle Opamp Oscillator
Written by delabs   
Tuesday, 21 October 2008 22:21

Here is the circuit of a Op-Amp based Square Wave Generator. One of the main application of this is in a Simple PWM circuit and Triangle Opamp Oscillator. The Slope of the Triangle wave is compared with a DC Level to derive a pulse width or On-Time proportional to a Voltage. This On-Time proportional to voltage is for a fixed oscillation rate based on C2-C3 and R15. The C2-C3 form a Unpolarized cap, This type is also used in crossover networks in speaker boxes. This is because, a plastic 4.7...

This post is a snippet, to see the full content visit this blog or http://www.dapj.net/. The blogs are listed at dapj Web.

Here is the circuit of a Op-Amp based Square Wave Generator. One of the main application of this is in a Simple PWM circuit and Triangle Opamp Oscillator. The Slope of the Triangle wave is compared with a DC Level to derive a pulse width or On-Time proportional to a Voltage.

This On-Time proportional to voltage is for a fixed oscillation rate based on C2-C3 and R15. The C2-C3 form a Unpolarized cap, This type is also used in crossover networks in speaker boxes. This is because, a plastic 4.7 uF (2 * 10uF series) is big and costlier, but a plastic cap is very stable and closer to an ideal cap.

Square and Triangle Opamp Oscillator

First you need to know that most opamps in such circuits can give a square wave, but very few can swing to the rails (+/-5). For designing take 75% of Vcc. CA3130 is one that can swing to rails like a CMOS gate.

Assuming the swing of output is around +/- 4V, the pin 10 + input will be at +/- 2V. When the cap is discharged at 0 V, let us take that the output is +, the cap charges to a little above +2, - input becomes dominant, so output swings negative. This discharges the cap to 0 and then charges it negatively upto -2. This in turn flips the output to + as pin 10 turns dominant. Hence this continues as a oscillation, with a nice triangle across the cap for the PWM comparator.

Dominant means more +, 0 is positive compared to -2V. Also -2.5 is negative compared to -2.2.

Read more: http://feedproxy.google.com/~r/SchematicsOfDelabs/~3/WBDLi8UjgPg/square-and-triangle-opamp-oscillator.html

Last Updated on Tuesday, 16 November 2010 14:35
 
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