Showing posts with label Power Supply. Show all posts

Wednesday, April 7

IC LM350. t oBattery Charger

The schematic diagram can be used for charging the 12V lead acid batteries.

The circuit is designed as a constant voltage source with a negative temperature coefficient. The transistor Q1 (BD 140) is used as the temperature sensor. The transistor Q2 is used to prevent the battery from discharging through R1 when the mains power is not available. The circuit is designed based on the voltage regulator IC LM350. The output voltage of the charger can be adjusted between 13-15 V by varying the POT R6.

The LM350 will try to keep the voltage drop between its input pin and the output pin at a constant value of 1.25V. So there will be a constant current flow through the resistor R1. Q1 act here as a temperature sensor with the help of components R6/R3/R4 which more or less control the base current of Q1. As the emitter/base connection of transitor Q1, just like any other semiconductor, contains a temperature coefficient of -2mV/°C, the output voltage will also show a negative temperature coefficient. That one is only a factor of 4 larger, because of the variation of the emitter/basis of Q1 multiplied by the division factor of P1/R3/R4. This results in approximately -8mV/°C. The LED will glow whenever the mains power is available.

Simple Nicad Battery Circuit

This simple and low cost battery charger uses a single transistor as a constant current source. The voltage across the pair of 1N4148 diodes biases the base of the BD140 medium power transistor. The base-emitter voltage of the transistor and the forward voltage drop across the diodes are relatively stable. The charging current is approximately 15mA or 45mA with the switch closed. This suits most 1.5V and 9V rechargeable batteries.

Monday, April 5

0-15 VDC Power Supply

This circuit of power supply, are very simple in the manufacture, the finding of his materials , is very easy and cost, small. The output voltage is stabilised and is regulated in the region from 0V until + 15V dc, with biggest provided current 1 A. The regulation becomes with the R2. The Q1 of is classic power transistor and it needs it is placed in heatsink, one and heating when it works continuously in the region of biggest current. The type of transformer is standard in the market.

Components ;
R1= 56ohm 2W Q1= 2N3055
R2= 330ohm Lin. pot. T1=220V@18V 1.5A
C1= 2200uF 35V
C2= 100uF 35V D1= 18V 1.5W zener
C3= 10uF 25V
C4= 220uF 25V
C5= 100nF 100V
GR1= 4 X 1N4007

Electronic Fuse Circuit

The power supply, with electronic stabilisation - mainly those of laboratories - it should they are protected from over current that emanates from short-circuits, erroneous association or damage of repaired appliance. The circuit offers effective protection in power supply with output voltage through to 45V DC. Transistor Q3 of is type in all cases BC148, while the types of Q1-2, as well as R1-2, depend from the biggest intensity of current, according to the table. The entry is connected in the exit power supply. Under regular conditions of work, the Q2 turn on, completely via the R1-Q1 and functions in the saturation. The output voltage is 2V roughly lower than the voltage of supply. If grow the dip of voltage, in the R2 at 0.7V. because short-circuit, then conduct the Q3 and the voltage between the collector and his emitter is 0.3V. the Q1-2, however is driver only when his voltage between the base of Q1 and emitter of Q2 is 1.4V at least. But in case of overcharge, this voltage is 0.7V+0.3V=1V, with result the circuit is regulated automatically in the predetermined biggest intensity. The transistors that I give in the table can be replaced with corresponding, it is enough they suit their characteristics.

Imax (A)	R1 (Ω)	R2 (Ω)	Q1	Q2	Q3
5	100	0.12	2Ν1613	2N3055	BC148
0.5	1000	1	BC107	2N1613	BC148
0.1	4700	4.7	BC107	2N1613	BC148

Regulated Power Supply 0V-30V DC

It is a simple circuit regulated power supply, based on the known LM 723, that drive a transistor Q1 [2N3055]. The regulation of voltage, of expense becomes with potentiometer R1 from 0v-30v DC roughly. In order to we achieve 30 V, will should the transformer of supply TR1, it gives all the current that it asks the load, differently the output voltage it will be found in the levels of 26 V roughly. Essential is the use of a good heatsink for transistor Q1, as well as good quality of potentiometer in the place of R1.

Part List ;
R1=1.2Kohm, C1=4700uF/63V, IC1=LM723, V1=0-30V DC, R2=680ohm, C2=100nF63V MKT, Q1=2N3055, TR1=220VAC/ 27V 4A, R3=0.33ohm/5W, C3=4.7nF63V MK,T B1=Brindge 100V 5A, S1=2x10A SW, R4=15Kohm, C4=220uF/63V, F1=0.5A, Fast Fuse, R5=3.9Kohm, P1=4K7 ,LOG. ,POT., F2=2A Slow Fuse

BROEDHIEN