DATASHEET and Circuit Diagram

The herein schematic appears typical stepper motor application with NJM3771. This stepper motor driver device is designed for use in microstepping applications in conjunction with the matching dual DAC (Digital-to-Analog Converter) NJU39610, according to the datasheet.

NJM3771 Dual Stepper Motor Driver features Dual chopper driver, 650 mA output current per channel, and Selectable slow/fast current decay for improved high-speed microstepping. Instead of capable for driving up to 650 mA continuous motor current, each channel of the NJM3771 consists of an H-bridge output stage, a logic section that controls the output transistors, an S-R flip-flop, and two comparators.

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The herein article contains information related on the method of closed loop control with a sensor and an actuator and how to apply the method to build a rudimentary On/Off heater controller (On/Off Temperature Control). The semiconductor components used to build this control circuit are thermistor, Zener diode, LED, relay, op-amp, and bipolar transistor.

Sections describe in this article are such essential elements of the control circuit, basic thermistor sensing circuit (using an op-amp without feedback as a comparator), thermistor sensing circuit using 2N222 transistor with 4 and output driver stage added, controlling a real actuator with a relay, and then finalising the circuit and improving the stability with Schmitt Trigger.

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The following schematic shows Hood Louver Driver Circuit Diagram using IC LM393. This circuit uses an LM393 op-amp comparator (U1) to monitor the Throttle Position Sensor (TPS) voltage. As seen in the diagram, the output of the LM393 drives a high-current PNP transistor (Q2), which turns on/off the hood louver solenoid relay.

As also stated in the LM393 datasheet, the advantages of LM393 are High precision comparators, Compatible with all forms of logic, Power drain suitable for battery operation, Reduced Vos drift over temperature, and more.

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The circuit diagram below shows the Accuphase P300V stereo power amplifier, an all stage push-pull circuit configuration that forms the base of the amplifier.

P300V Stereo Power Amplifier unit assemblies both PNP and NPN power transistors with 10 parallel push-pull circuits, MOSFET cascode drive stage, NPN transistor for Class A predrive stage, Power circuits for drive stage, Input differential complementary push-pull amps, and PNP transistor for Class A predrive stage.

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The following injector driver circuit is designed to work with most Engine Control Module (ECM) as well. It is used to drive the other two injectors in a four injector throttle body in which ECM drives two of them and this device uses one of the injector drive lines as the trigger signal to drive the other two.

This Injector Driver Schematic Diagram uses two injector driver chip LM1949 that controlled voltage drops in the ECM, two TIP122 big transistors (Q1 and Q3), two NPN transistors (Q2 and Q4) to invert the signal from the op-amp and limit the voltage swing to +5V to protect the input on the LM1949.

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The following schematic diagrams DC-DC Step Down Converter using ZTX788B PNP silicon planar transistor as a switch element in a 12V to 5V circuit.

The circuit shows the general form of the step down or ‘Buck’ converter using a PNP transistor operating at 100kHz and supplies a 2A load.

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The schematic herein diagrams a very high voltage, high current booster which allows an op amp to control up to 300W positive outputs up to a staggering 1000V. The high voltage is generated by a switching DC-DC converter which forms an integral part of the booster. This circuit operates in a switching mode performance.

This so called ‘Son of Godzilla Booster’ using LM3524 switching regulator chip to pulse width modulate the transistors which provide switched 20 kHz drive to the  step-up transformer. The transformer’s output is fed back to the LF411 op amp which controls the input to the LM3524 switching regulator.

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The schematic shows you with the Simplified Half-Bridge Output Inverter Circuit. The circuit diagram is called to be Full-Bridge simplification since the number of equivalent Insulated-Gate Bipolar Transistor (IGBTs) is now a half even the number of diodes in the output rectifier is doubled.

When one of IGBTs is in ON, the other is OFF. During the positive half wave, X1 is ON and X2 is OFF so that DA and DB work as output rectifier while DC & DD are OFF and vice versa.

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If you need a bipolar NPN transistor with dynamic characteristics and lot to lot minimum spread for your light ballast applications, you may consider the BUD42D 4A, 650V, 25W Power Transistor. The schematic below is the typical inductive load switching drive circuit diagram of the BUD42D.

The device has features such free wheeling diode built in, flat DC current gain, antisaturation network, transient voltage suppression capability, and “6 Sigma” Process Providing Tight and Reproducible Parameter Spreads.

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The following DC power supply (PSU) is designed for the ham radio transceivers. It such a regulated DC power supply with short circuit safe and current limiter. This PSU can deliver 20Amps at 13.8V using a simple 12V regulator of the IC7812.

This power supply circuit was built with semiconductors as follows: transistors (BC 557B, BD330, 2N5683, BC547), 7812 IC Regulator, various resistors, capacitors (40.000uF, 33nF, 1uF Tantal, 100nF) and etc.

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