Description

Here is the simplest melody generator circuit you can make using an IC.The  UM66 series are CMOS IC’s  designed for using in calling bell, phone and toys. It has a built in ROM programmed for playing music. The device has very low power consumption.Thanks for the CMOS technology.The melody will be available at pin3 of UM66 and here it is amplified by using Q1 to drive the speaker.Resistor R1 limits the base current of Q1 within the safe values.Capacitor C1 is meant for noise suppression.

Notes

• Power supply  must be between 1.5V & 4.5V .Do not exceed 4.5 V.
• Speaker can be driven with external NPN  transistor.
• Melody begins from the first note if power is reseted.
• Assemble the circuit on a good quality common board.
• If transistor HE8050S is not available use any NPN transistor like BC548 or 2N2222.

Circuit Diagram.Click to Enlarge .                             UM66 Necessary Data.

Description

This is the circuit diagram of a simple 19 watt amplifier using IC LA4440 from Sanyo.It uses very less components other than the IC LA4440.A very high quality circuit with respect to its cost and ideal for beginners.

Here IC LA 4440 is wired as a bridge amplifier to deliver a 19 W Rms on a 4 Ohm speaker. The IC has built in thermal, over voltage and short circuit protection.The IC also incorporates a audio muting function,but that is not used here.

Notes .

• Use a 12 V DC power supply able to deliver at least 3A current . IC can with stand up to 25 volt , but I prefer it should not be nothing more than 16V.
• Don’t forget to fit a proper heat sink with IC.
• Assemble the board on a good quality PCB.Carefully understand the specifications of LA 4440 given below before proceeding
• Use a 4 Ohm speaker as load. 8 Ohm speaker can also be used but the power output will drop to half (9.5 W) .
• For stereo assemble two copies of the amplifier given here.

Circuit Diagram.Click to Enlarge. LA 4440 Specifications.

Description.

The circuit shows that the output of IC1 555 IC,which is designed for a duty cycle of 0.8mSec,with a frequency of 120Hz and 300 mA peak current, is used to drive the infra red LED,D1.From the connection it is clear that the diodes D1 and D2 are on the same line,just a few centimeters apart, on the breadboard.Thus diode D2 receives the infra-red output from the diode D1.The diode signal, which is given to the inverting terminal of the op-amp IC LM 358. gets amplified and its peak is detected by diode D4 and capacitor C4.The forward voltage produced by diode D4 is compensated by diode D3 with R5 and R6.According to the distance between the infra-red transmitter and receiver, a proportional DC voltage is fed to the inverting input of IC2.According to the output of the comparator the LED is turned ON and OFF and this is detected by the transistor Q1.Thus the relay is driven according to the output of Q1.The comparator output is set according to the value of the pot.

This circuit is mainly used for liquid level detection or proximity detection. It operates detecting the distance from the target by reflection of an infra-red beam.The biggest advantage of this circuit is that there is no physical contact with the liquid whose level is to be measured.The range is set by adjusting the pot.Range can vary, depending on infra-red transmitting and receiving LEDs used and is mostly affected by the color of the reflecting surface. Black surfaces lower greatly the device’s sensitivity.

Notes .

Use a good quality regulated power supply .The sensor diodes must not be subjected directly to other light sources.

Parts List .

1. Resistance R1                       10K(4W)
2. Resistance R2,R5,R6,R9     1K(4W)
3. Resistance R3                       33R(4W)
4. Resistance R4,R8                 1M(4W)
5. Trimmer Cermet R7           10K
6. Resistance R10                    22K(4W)
7. Capacitance C1,C4              1 uF(63V)
8. Capacitance C2                   47pF(63V)
9. Capacitance C3,C5,C6      100uF(25V)
10. Diode D1                             IR LED
11. Diode D2                             IR Photo-Diode
12. Diode D3,D4                       1N4148(75W/150mA)
13. Diode D5                             LED
14. Diode D6,D7                      1N 4002
15. PNP Transistor Q1           BC 558(45V/800mA)
16. Timer IC IC1                     NE 555
17. IC 2                                     LM358
18. IC 3                                     7812
19. Relay                                  SPDT(2A/220V)
20. J1                                        Two ways output socket

Circuit Diagram.Click to Enlarge.

     Circuit  Designed by:  K. John Joseph

Description

This is the circuit diagram of a dual adjustable power supply using IC’s LM 317 & LM 337.LM 317 is able to deliver a maximum of 1.5 A at a range of 1.2 V to +30V .LM 337 is the negative complement of LM317.They also have a built in short circuit protection.

Here the circuit is wired to produce a dual adjustable output of ( +15 , 0 , -15 ).The capacitors C1 to C8 provides filtering and ripple rejection.Resistors R1 & R2 controls output of LM 317.Resistors R3 & R4 controls the output of LM 337 .R1 and R4 can be turned to vary the positive and negative voltages.This circuit is a must on an electronic hobbyists workbench.

Notes

1. The transformer should be anything that produces a min of 3 A with (24 0 24 ) output voltage.
2. The voltage range can be further increased by increasing transformer output within the limits of IC.
3. Do not connect a load drawing more than 2A at output.The IC,s must be fitted with heat sinks for better protection.

Parts List

C1, C2 2200 uF 50V Electrolytic Capacitor
C3, C4, C5, C7 2.2 uF 50V Electrolytic Capacitor
C6, C8 100 uF 50V Electrolytic Capacitor
R1, R4 5K Potentiometer
R2, R3 220 Ohms 1/4 W Resistor
D1 to D4 IN 4007 Diodes
U1 LM317 U2 LM337 T1 24 0 24 Center Tapped 2 Ampere Transformer
S1 SPST 2 Ampere Switch
Extra Heat sinks for two IC’s , Power Cord, Casing, Wire etc

Circuit Diagram.Click to Enlarge.

Description 

This is the circuit diagram of a 1.2 V to 25 V voltage regulator using IC LM 117 IC.The LM117 series of adjustable 3-terminal positive voltage regulators are able to provide in excess of 0.5A over a 1.2V to 37V output range. They are very easy to handle and require only two external resistors to set the output voltage.

This power supply is able to deliver a maximum of 0.5 A current.The circuit is easy to assemble and provides great results.Resistances R1 and R2 are used for voltage adjustment.Vary pot R2 to get the required voltage.If exact value components are not available try the nearest ones.Parts list is given with the circuit diagram.

Notes .

1. For getting a 1.2 A output current replace LM117 with LM317.All connections are same.
2. To reduce min output voltage from 1.2 volt to 0V connect two IN4007 diodes in series to the output ( 1.2  – (0.7+0.7) = -0.2 V  ie ; 0 V approx).
3. Fit the IC with a suitable heat sink.
4. You can use as less as 5V DC as input voltage.No problem but remember the maximum regulated output voltage will also decrease almost by the same fraction. Here a minimum 28V   2A DC input is needed for the IC  as shown in figure.

Circuit Diagram & Parts List                                  LM 117 Pin Out Diagrams