Multi Output Instrument Power Supply

 Power-Supplies  No Responses »
Oct 112006
 
Multi Output Instrument Power Supply

Every electronic gadget primarily needs a D.C, power supply to energize it. It also forms the basic requirement for any constructional project. consequently there is a need to obtain multiple voltage values for cost reduction, convenience and compact arrangement for all the above applications List Of Components For Power Supply. 1. Transformers X1-6-0-6 (500 ma), X2-12-0-12 (500ma) 2. Semiconductors IC6-7805, IC7-7808, IC8-7908, D1 to D10-IN4007, D11 and D12 – 12v, 1W, Zener 3. Resistors. R1 and R2 – 100E 1/2 W CFR 4. Capacitors. C 40v C5 and C8 – 1000 Mfd , C1 – 2200 Mfd, C5 and C7 Read More …

 Posted by admin at 8:12 PM

5V -1A Power Supply using LM2575

 Power-Supplies  No Responses »
May 032005
 
5V -1A Power Supply using LM2575

A Power Transistor which is having a drop of 4 Volts across it and passing 3 amps thru it, may dissipate around 12 Watts of Heat, This is the problem in Series Regulators. While a Saturated Transistor or Mosfet with 1 Volts across and 3 Amps Thru will be just 3 Watts. But then a fully on transistor or mosfet cannot be controlled or regulated, for that we turn it ON and OFF very fast so that the right amount of current or voltage is delivered. The way this is done is PWM – Pulse Width Modulation. In this the Read More …

 Posted by admin at 7:06 AM  Tagged with:

Digital 5V Power Supply using L296

 Power-Supplies  No Responses »
Apr 222005
 
Digital 5V Power Supply using L296

This circuit is derived from an application note of L296, It is a Power Switching Regulator from ST. The advantage of using a switching regulator is that there is not much Heat Dissipation in this circuit. If you had to build the same with a series regulator, it would be very big due to external transistor and a huge heat sink. This circuit takes a small place on PCB, efficiency is high so power is saved and reliability of product improves, lastly the thermal gradients within the cabinet is avoided so that any form of drift or component specs variation Read More …

 Posted by admin at 2:57 AM  Tagged with: ,

Battery Level Indicator

 LED-Circuits, Opamp-Circuits, Power-Supplies  No Responses »
Oct 312004
 
Battery Level Indicator

This circuit uses a LM339 pdf, a quad comparator. LM339 pdf can work on single or dual supplies, it has a open collector output that can drive 15mA, low power consumption. The circuit is an untested design but it should work. I did it as many searches were made in my webpages with these keywords. There are many better circuits in the various circuit archives i have linked on the front page, you just have to look around. When you measure the open circuit voltage of a battery with a high impedance DMM (10M), the value may be a bit Read More …

 Posted by admin at 1:18 AM  Tagged with:

Dual Polarity Power Supply

 Power-Supplies  No Responses »
Oct 282004
 
Dual Polarity Power Supply

This supply gives both positive and negative outputs. Appropriate Fuses should be used to protect from fire hazard and overload of transformer. The Filter capacitor C1 4700uF has an impedance of Xc = 1 / (2 * 3.14 * f * C) which comes to 0.6 ohms at 50 Hz. The impedance of the load at 2A for 24V is R = V / I that is 12 Ohms which is more than 20 times the impedance of the capacitor at 50 Hz. That means less than 1 / 20 of ripple current will flow thru the load. The Regulator Read More …

 Posted by admin at 7:40 PM

Single Polarity Power Supply

 Power-Supplies  No Responses »
Oct 282004
 
Single Polarity Power Supply

This circuit uses a PNP Power Transistor TIP2955, you can use any other according to your current and voltage requirement. Look at R2 a 10 Ohm resistor, when the current in your load to the power supply is less than 70mA the voltage across R2 is less than 10E * 70mA = 700mV right. The base emitter junction of Q1 will be biased or turned on around 700mV, less than 700mV the transistor just does nothing. When the current in your load goes over 70mA the voltage across R2 goes above 700mV and a small base current Ib flows from Read More …

 Posted by admin at 7:39 PM

Battery Backup Supply

 Embedded-Systems, Power-Supplies  1 Response »
Oct 282004
 
Battery Backup Supply

This is a 9V power supply which will work even on power failure. It uses a rechargeable battery and regulators. A transformer with 15-0-15 AC volts output is required. In the first regulator U1 the output is lifted up by 1.4V and in the second regulator U2 by a resistor divider. In the second regulator the voltage across resistor R3 is 5V, so the current is 5V / 1K = 5mA this adds to the quiescent current of 5mA from the regulators ground terminal and flows into the resistors R1 and R2 in parallel which form 404 ohms, 10mA thru Read More …

 Posted by admin at 7:37 PM  Tagged with:
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