3-3.5 Watt FM transmitter circuit

This is 3-3.5 Watt FM transmitter circuit. With this power, it should be able to reach 3-5 KM distance. The frequency range is about 90-110 MHz.

Component list

Part	Total Qty.	Description
R1,R4,R14,R15	4	10K 1/4W Resistor
R2,R3	2	22K 1/4W Resistor
R5,R13	2	3.9K 1/4W Resistor
R6,R11	2	680 Ohm 1/4W Resistor
R7	1	150 Ohm 1/4W Resistor
R8,R12	2	100 Ohm 1/4W Resistor
R9	1	68 Ohm 1/4W Resistor
R10	1	6.8K 1/4W Resistor
C1	1	4.7pF Ceramic Disc Capacitor
C2,C3,C4,C5,C7,C11,C12	7	100nF Ceramic Disc Capacitor
C6,C9,C10	3	10nF Ceramic Disc Capacitor
C8,C14	2	60pF Trimmer Capacitor
C13	1	82pF Ceramic Disc Capacitor
C15	1	27pF Ceramic Disc Capacitor
C16	1	22pF Ceramic Disc Capacitor
C17	1	10uF 25V Electrolytic Capacitor
C18	1	33pF Ceramic Disc Capacitor
C19	1	18pF Ceramic Disc Capacitor
C20	1	12pF Ceramic Disc Capacitor
C21,C22,C23,C24	4	40pF Trimmer Capacitor
C25	1	5pF Ceramic Disc Capacitor
L1	1	5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L2,L3,L5,L7,L9	5	6-hole Ferroxcube Wide band HF Choke (5 WDG)
L4,L6,L8	3	1.5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L10	1	8 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm
D1	1	BB405, BB102 or equal (most varicaps with C = 2-20 pF [approx.])
Q1	1	2N3866
Q2,Q4	2	2N2219A
Q3	1	BF115
Q5	1	2N3553
U1	1	7810 Regulator
MIC	1	Electret Microphone
MISC	1	PC Board, Wire For Antenna, Heatsinks

Source: electronic-lab.com

Mini FM Transmitter

Here the schematic diagram of mini and simple fm transmitter.

Supply voltage : 1.1 - 3 Volts
Power consumption : 1.8 mA at 1.5 Volts
Range : 30 meters max. at 1.5 Volts

Here the PCB Layout:

Visit this page for complete explanation

3 Line Mixer

Actually, you can modify this circuit become more than 3 lines mixer. Just add and repeat the input parts (P=10K R=22K).

Schematic diagram:

Component placement:

PCB layout:

500 Watt Power Inverter

Here the 500 Watt power inverter schematic diagram.

Designed by: Syed Ashad Mustafa Younus
Revised by: Ronnie B. Tabanao

Click the image to get bigger size of schematic diagram and then save the image... or download the circuit diagram from here

Positive(+) to Negative(-) Voltage Inverter

This simpe circuit will convert the positive input voltage become negative voltage.

Schematic diagram:

Component list:

Part	Total Qty.	Description
R1	1	24K 1/4 Watt Resistor
R2	1	56K 1/4 Watt Resistor
C1	1	3300pF 25V Ceramic Capacitor
C2	1	47uF 25V Electrolytic Capacitor
C3	1	10uF 25V Electrolytic Capacitor
D1, D2	2	1N4148 Silicon Diode
U1	1	555 Timer
MISC	1	Wire, Board

Notes:

1. V+ can be anywhere from 4 to 16V. -V is one volt less than V+. So for -12V output, use +13V input. The maximum current output of the circuit is about 280mA, more than enough for a few op amps.
2. For better regulation, a 79LOxx series regulator can be used.
3. A zener diode may also be used to regulate the output voltage.

3-30 V/2.5 A Adjustable Stabilized Power Supply

This is Simple 3-30 volt adjustable and stabilized power supply circuit. You can use this circuit for general purpose.

Here the schematic diagram:

Component list:

R1 = 560R 1/4W	C1 = 100nF
R2 = 1,2 K 1/4W	C2 = 2200uF 35-40V
R3 = 3,9 K 1/4W	C3 = 100 pF
R4 = 15K 1/4W	C4 = 100uF/ 35V
R5 = 0,15R 5W
D = B40 C3300/2200, 3A rectifier bridge
P1 = 10K potesiometer	TR1 = BD 135
IC = LM723	TR2 = 2N3055

PCB layout:

Components placement:

For complete explanation, circuit's works and how to build this circuit into the box, download the full tutorial here

Universal Pre-Amplifier

Here the universal pre-amplifier schematic diagram for common input device:

Download the schematic in PDF format

2 Way Cross-Over 3500 Hz (bass and treble)

This is 2 way cross-over for your speaker system. This circuit will handle 2 speaker that are woofer (low frequency) an tweeter (high frequency).

The result will shown as below picture:

Here the schematic diagram of the circuit:

Visit this page for PCB layout and complete explanation about the circuit.