6V Gel Cell Charger Circuit

This is the diagram of 6V Gel Cell charger. The circuit is using NE555 timer as oscillator and TPI31T switching transistor. The schematic diagram designed by Tony Van Roon.

Parts List:

R1 = 22 ohm, 1W R2 = 270 ohm R3 = 220 ohm *R4 = 715 ohm, 1% *R5 = 3.57K, 1% *R6 = 1.40K, 1% *R7 = 1.47K, 1%

C1 = 100nF C2 = 100nF D1 = 1N4001 T1 = TIP31A, B, C (or equivalent) U1 = Timer IC NE555V (or equivalent) S1 = Toggle switch, ON-OFF

* Resistors type are carbon, 1/4 watt, 5% tolerance, unless otherwise indicated.

6V Gel Cell Charger circuit source page

6-8A / 0-28V Variable Power Supply Circuit

This is the schematic diagram of variable power supply. The output voltage of this power supply circuit can be adjust from 0V to 28V DC, while the current output is static the rang is about 6A up to 8A.

Parts List:

R1 = 2K2 Ohm 2,5 Watt R2 = 240 Ohm R3,R4 = 0.1 Ohm 10 Watt R7 = 6K8 Ohm R8 = 10K Ohm R9 = 47 Ohm 0.5 Watt R10 = 8K2 Ohm C1, C7, C9 = 47nF C2 = 4700uF/50v – 6800uF/50v C3, C5 = 10uF/50v C4, C6 = 100nF C8 = 330uF/50v C10 = 1uF/16v C11 = 22nF

D1…D4 = four MR750 diodes (MR750 = 6 Ampere diode) or 2 x 4 1N5401 diodes. D5 = 1N4148, 1N4448, 1N4151 D6 = 1N4001 D10 = 1N5401 D11 = LED D7, D8, D9 = 1N4001 TR = 2 x 15 volt (30volt total) 6+- Ampere IC1 = LM317 T1, T2 = 2N3055 P1 = 5k P2 = 47 Ohm or 220 Ohm 1 Watt P3 = 10k trimmer pot F1 = 1 Amp F2 = 10 amp

Source: circuitdiagram.net

Electronic Siren Circuit

This is the schematic diagram of electronic siren circuit. The sound produced imitates the rise and fall of an American police siren. When very first switched on, the 10uF capacitors is discharged and each transistors are off. When the push button switch is pressed to 10uF capacitor will charge via the 22k resistor. This voltage is applied towards the base of the BC108B which will turn on slowly. When the switch is released the capacitor will discharge via the 100k and 47k base resistors and also the transistor will slowly turn off. The change in voltage alters the frequency of the electronic siren.

Electric current drain is fairly high in this electronic siren circuit so a appropriate power supply is needed. The duration the tone takes to rise and fall is determined by the 10uF and 22k resistor. These values may possibly be varied for various effects.

Simple LM358 Mic Preamplifier

This is a simple LM358 microphone preamplifier schematic diagram. The pre-amp circuit is very easy to build and.. it's a low cost project... The variable resistor R5 is to adjust the LM358 op-amp gain. The LM358 has dual op-amp circuit modules, you may use a single LM358 to build two channels mic preamplifier.

Parts List:
R1, R3, R4 = 10K
R2 = 1K
R5 = 100K-1M Potensiometer
C1 = 0.1uF
C2 = 4.7uF/16V
IC1 = LM358 dual op-amp single power supply
Mic = Electret Microphone