CA3140 | Electronic Project Circuits

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Buffer Opamps by CA3140

The buffer electronic with IC Opamps by CA3140 (More circuits use CA3140) or LF353 or TL072.
If output impedance of a point is a high value then connecting another circuit at that point will load it resulting in malfunction or error. Buffers are used as interface between circuits. Low impedance of an output means it can source sink lot of current, when you need 2 opamps use LF353 (More circuits use LF353)or TL072 which are dual opamps. A non-inv FET input is the best buffer, for inverting buffer use high R values Using very high R values like 2.2M or higher requires a glass epoxy PCB and guard rings around pin 2, 3 to prevent leakage currents on the PCB reaching the PINs. Also moisture and dust has to be prevented by using RTV coating or Varnish. Use 78L05 79L05 for the dual supply required by this circuit.

Read more source:http://schematics.blogspot.com/2004/10/buffer-opamps.html

Be the first to comment - What do you think? Posted by admin - May 13, 2008 at 6:05 pm

Categories: Basic electronics Tags: buffer digital circuits, Buffer opamp, CA3140, TL072

Speed-limit Alert with CA3140,4069,4098

Wireless portable unit Adaptable with most internal combustion engine vehicles

This circuit has been designed to alert the vehicle driver that he/she has reached the maximum fixed speed limit (i.e. in a motorway). It eliminates the necessity of looking at the tachometer and to be distracted from driving.
There is a strict relation between engine’s RPM and vehicle speed, so this device controls RPM, starting to beep and flashing a LED once per second, when maximum fixed speed is reached.
Its outstanding feature lies in the fact that no connection is required from circuit to engine.

Parts:
[...]
C1,C7_________100µF 25V Electrolytic Capacitors
C2,C3_________330nF 63V Polyester Capacitors
C4-C6___________4µ7 25V Electrolytic Capacitors
D1,D5______Red LEDs 3 or 5mm.
D2,D3________1N4148 75V 150mA Diodes
D4________BZX79C7V5 7.5V 500mW Zener Diode
IC1__________CA3140 or TL061 Op-amp IC
IC2____________4069 Hex Inverter IC
IC3____________4098 or 4528 Dual Monostable Multivibrator IC
Q1,Q2_________BC238 25V 100mA NPN Transistors
L1_____________10mH miniature Inductor (see notes)
BZ1___________Piezo sounder (incorporating 3KHz oscillator)
SW1____________SPST Slider Switch
B1_______________9V PP3 Battery (see notes)
Clip for PP3 Battery
[...]
Please read more at the original source:http://www.redcircuits.com//Page23.htm
Thank you.

Be the first to comment - What do you think? Posted by admin - September 14, 2007 at 9:58 pm

Categories: Audio diagram, Automotive Tags: CA3140, speed alarm, speed limit alert

MJ2955 Switching Power Supply 12V 10Amp

The switching power supply provides 12 volts, at 10 amps, maximum, using a discrete transistor regulator with an op-amp functioning as a comparator in the feedback circuit.

With reference to the schematic, the front panel power-on light is not shown. There is no adjustable current limiter in this unit, although R1, R2, R3, Q2, R8, R9, C5 and Q4 set the current limit to approximately 10 amps. As you can see, the design is very similar to that of a linear power supply, except that L1, and D1 have been added, and U1 operates in a switching mode as a comparator with a small amount of hystersis. The switching frequency of this unit varies with the output current drawn by the load. This is an undesireable feature, which is why PWM regulators are used today. With a PWM regulator, the switching frequency is constant and will produce spurs only at known discrete frequencies rather than spurs at all frequencies. The Darlington-connected pass transistor block in the schematic is there twice (in parallel) for robustness. R4 in an internal trim-pot that can set the output voltage anywhere between 5 to 15 volts.

Read More Source :http://members.tripod.com/michaelgellis/power4.html