Sunday, September 29, 2013

HANDY 0 12V DC POWER SUPPLY ELECTRONIC DIAGRAM


HANDY 0-12V DC POWER SUPPLY ELECTRONIC DIAGRAM

For heat protection, heat sink is needed for the BD679 transistor. It is because it will be over tempered when works more than 200mA.

FEATURES:
0v to 12 volt output:
- 700mA with M 2155
- 1.4amp with M 2156
- 1A with 16v AC 1.5 amp plug pack
More...

Friday, September 27, 2013

Push Button Relay Selector

This circuit was designed for use in a hifi showroom, where a choice of speakers could be connected to a stereo amplifier for comparative purposes. It could be used for other similar applications where just one of an array of devices needs to be selected at any one time. A bank of mechanically interlocked DPDT pushbutton switches is the simplest way to perform this kind of selection but these switches aren’t readily available nowadays and are quite expensive. This simple circuit performs exactly the same job. It can be configured with any number of outputs between two and nine, simply by adding pushbutton switches and relay driver circuits to the currently unused outputs of IC2 (O5-O9).

Gate IC1a is connected as a relax-ation oscillator which runs at about 20kHz. Pulses from the oscillator are fed to IC1b, where they are gated with a control signal from IC1c. The result is inverted by IC1d and fed into the clock input (CP0) of IC2. Initially, we assume that the reset switch (S1) has been pressed, which forces a logic high at the O0 output (pin 3) of IC2 and logic lows at all other outputs (O1-O9). As the relay driver transistors (Q1-Q4) are switched by these outputs, none of the relays will be energised after a reset and none of the load devices (speakers, etc) will be selected. Now consider what happens if you press one of the selector switches (S2-S5, etc). For example, pressing S5 connects the O4 output (pin 10) of IC2 to the input (pin 9) of IC1c, pulling it low.

Pushbutton relay selectorThis causes the output (pin 10) to go high, which in turn pulls the input of IC1b (pin 5) high and allows clock pulses to pass through to decade counter IC2. The 4017B counts up until a high level appears at its O4 output. This high signal is fed via S5 to pin 9 of NAND gate IC1c, which causes its output (pin 10) to go low. This low signal also appears on pin 5 of IC1b, which is then inhibited from passing further clock pulses on its other input (pin 6) through to its output (pin 4), thus halting the counter. So, the counter runs just long enough to make the output connected to the switch that is pressed go high. This sequence repeats regardless of which selector switch you press, so the circuit functions as an electronic interlock system.

Each relay driver circuit is a 2N7000 FET switch with its gate driven from one output of IC2 via a 100W resistor. The relay coil is connected from the drain to the +12V supply rail, with a reverse diode spike suppressor across each coil. If you want visual indication of the selected output, an optional indicator LED and series resistor can be connected across each relay coil, as shown. For selecting pairs of stereo speakers, we’d suggest the use of relays like the Jaycar SY-4052. These operate from 12V and have DPDT contacts rated for 5A. Note that although four selector switches are shown in the circuit, only two relay drivers are shown because of limited space. For a 4-way selector, identical relay drivers would be driven from the O2 and O3 outputs of IC2.
More...

Wednesday, September 25, 2013

A Bedside Lamp Timer Circuit

30 minutes operation, Blinking LED signals 6 last minutes before turn-off

The purpose of this circuit is to power a lamp or other appliance for a given time (30 minutes in this case), and then to turn it off. It is useful when reading at bed by night, turning off the bedside lamp automatically in case the reader falls asleep... After turn-on by P1 pushbutton, the LED illuminates for around 25 minutes, but then it starts to blink for two minutes, stops blinking for two minutes and blinks for another two just before switching the lamp off, thus signaling that the on-time is ending. If the user want to prolong the reading, he/she can earn another half-hour of light by pushing on P1. Turning-off the lamp at users ease is obtained by pushing on P2.

Circuit diagram:

bedside_220 volt ac  lamp timer schematic circuit diagram A Bedside Lamp Timer Circuit Diagram

Parts:

Resistors
R1 = 1K
R2 = 4K7
R3 = 10M
R4 = 1M
R5 = 10K

Capacitors
C1 = 470µF-25V
C2-C4100nF-63V

Semiconductors
C1 = 470µF-25V
C2-C4 = 100nF-63V
D1-D4 = 1N4002
D5 = 5mm. Red LED
IC1 = CD4012
IC2 = CD4060
Q1 = BC328
Q2 = BC547

Miscellaneous
P1,P2 = SPST Pushbuttons
T1 = 9+9 Volt Secondary 1VA Mains transformer
RL1 = 10.5V 470 Ohm Relay with SPDT 2A 220V switch
PL1 = Male Mains plug
SK1 = Female Mains socket

Circuit operation:
Q1 and Q2 form an ALL-ON ALL-OFF circuit that in the off state draws no significant current. P1 starts the circuit, the relay is turned on and the two ICs are powered. The lamp is powered by the relay switch, and IC2 is reset with a positive voltage at pin 12. IC2 starts oscillating at a frequency set by R4 and C4. With the values shown, pin 3 goes high after around 30 minutes, turning off the circuit via C3. During the c6 minutes preceding turn-off.

The LED does a blinking action by connections of IC1 to pins 1, 2 & 15 of IC2. Blinking frequency is provided by IC2 oscillator at pin 9. The two gates of IC1 are wired in parallel to source more current. If required, a piezo sounder can be connected to pins 1 & 14 of IC1. Obviously, timings can be varied changing C4 and/or R4 values.

Source : www.extremecircuits.net

More...

Monday, September 23, 2013

Fuse Box BMW 528I 1982 Diagram

Fuse Box BMW 528I 1982 Diagram - Here are new post for Fuse Box BMW 528I 1982 Diagram.

Fuse Box BMW 528I 1982 Diagram



Fuse Box BMW 528I 1982 Diagram
Fuse Box BMW 528I 1982 Diagram

Fuse Panel Layout Diagram Parts: normal speed relay, high speed relay, low beam check relay, high beam relay, low beam relay, fog light relay, main relay, purge valve relay, fuel pump relay, horn relay, wiper control unit, unloader relay.
More...

Saturday, September 21, 2013

Roper 2079b00 Wiring Diagram

Roper 2079b00 Wiring Diagram
(click for full size image)


The Part of Roper 2079b00 Wiring Diagram:black wire, neutral grounded, ind lite, relay coil, clock, bake eleh, door latch, red wire,

More...

Wednesday, September 11, 2013

Top Performance LA4446 Stereo Audio Amplifier Circuit

LA4446 is of similar series IC as LA4440, but it is meant for dual or stereo 5.5Watt RMS outputs. While 4440 gives 6Watt outputs at dual mode, this gives almost same but with much smaller package size. The IC package is mall but it provides same functionality and special features like LA4440. These are,
  1. Low pop noise at power ON/OFF time
  2. Good ripple rejection: 46dB(typ)
  3. Good channel separation
  4. Low residual noise (Rg=0)
  5. On chip protectors as Thermal protector, Over-voltage/Surge Protector, and pin short protector
The below circuit is the application circuit of LA4446 IC. 

Top Performance LA4446 Stereo Audio Amplifier Circuit

More...

Tuesday, September 3, 2013

Mini Drill Speed Regulator Using Voltage Regulator

With an integrated voltage regulator connected reverse to a mini drill can be adjusted speed within certain limits so that it remain constant, independently of load. In the scheme presented below the electronic speed control is made by a voltage regulator, allowing use of motor which require a supply voltage from 2.5 V to 12 V at a maximum current absorbed by an 1A. Output voltage is determined by the ratio of resistances R1 and R2. Uout = (R1 + R2) Uc/R2. Uc is equal to -2.23 V for 79GU voltage regulator.

Mini Drill Speed Regulator Circuit diagram


Integrated controller is designed to keep constant the value of -2.23 V, the voltage from common terminal .
With the P2 potentiometer can be adjusted the degree of coupling (coupling the output voltage increases with increasing output current). Thus remains constant preset speed. Maximum voltage measured when the P2 is turned up must be about 20% lower than the maximum allowable voltage of the motor (if is not, the value of R1 should be reduced or enlarged accordingly). Voltage regulator is designed with thermal protection, but it must be mounted on a properly dimensioned radiator.
More...

Sunday, September 1, 2013

FM Beacon Broadcast Transmitter 88 108 MHz

This circuit will transmit a continuous audio tone on the FM broadcast band (88-108 MHz) which could used for remote control or security purposes. Circuit draws about 30 mA from a 6-9 volt battery and can be received to about 100 yards. A 555 timer is used to produce the tone (about 600 Hz) which frequency modulates a Hartley oscillator. A second JFET transistor buffer stage is used to isolate the oscillator from the antenna so that the antenna position and length has less effect on the frequency.  

Fine frequency adjustment can be made by adjusting the 200 ohm resistor in series with the battery. Oscillator frequency is set by a 5 turn tapped inductor and 13 pF capacitor. The inductor was wound around a #8 X 32 bolt (about 3/16 diameter) and then removed by unscrewing the bolt. The inductor was then streached to about a 3/8 inch length and tapped near the center.

FM Beacon Broadcast Transmitter Circuit Diagram
The oscillator frequency should come out somewhere near the center of the band (98 MHz) and can be shifted higher or lower by slightly expanding or compressing the inductor. A small signal diode (1N914 or 1N4148) is used as a varactor diode so that the total capacity in parallel with the inductor varies slightly at the audio rate thus causing the oscillator frequency to change at the audio rate (600 Hz).

The ramping waveform at pins 2 and 6 of the timer is applied to the reversed biased diode through a large (1 Meg) resistor so that the capacitance of the diode changes as the ramping voltage changes thus altering the frequency of the tank circuit. Alternately, an audio signal could be applied to the 1 Meg resistor to modulate the oscillator but it may require an additional pullup resistor to reverse bias the diode. The N channel JFET transistors used should be high frequency VHF or UHF types (Radio Shack #276-2062 MPF102) or similar.
More...