Oct 28th, 2009
by Electronics Online.
This is an LED pulse effect circuit. The effect result of this circuit is that the LED goes from off state, lights up gradually, then dims gradually.
This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive. R4 and C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds.
R1,R2 _________4K7 ohm
R3 _________22K ohm
R4 _________2M2 ohm (See Notes)
R5 _________10K ohm
R6 _________47R ohm (See Notes)
C1 _________1µF/ 63V Polyester Capacitor
D1 _________5mm. LED (See Notes)
IC1 _________LM358 Low Power Dual Op-amp
Q1 _________BC337 NPN Transistor
Oct 18th, 2009
by Electronics Online.
Wanna to build an inverter circuit..? This is an ordinary transistorised inverter circuit capable of driving medium loads of the order of 40 to 60 watts using battery of 12V, 15 Ah or higher capacity. This inverter will convert 12V DC input to become 230V AC in output.
Transistors T1 and T2 (BC548) form a 50Hz multivibrator. For obtaining correct frequency, the values of resistors R3 and R4 may have to be changed after testing. The complementary outputs from collectors of transistors T1 and T2 are given to PNP darlington driver stages formed by transistor pairs T3-T4 and T6-T7 (utilising transistors BD140 and 2N6107).
Jun 8th, 2009
by Electronics Online.
This is very simple FM Radio receiver with only use 1 transistor.
Not only simple and easy to build, this circuit also inexpensive. You can build this circuit with low risk.
Mar 31st, 2009
by Electronics Online.
This amplifier circuit design is based on the 18 Watt Audio Amplifier, and was developed mainly to satisfy the requests of correspondents unable to locate the TLE2141C chip. It uses the widespread NE5532 Dual IC but, obviously, its power output will be comprised in the 9.5 – 11.5W range, as the supply rails cannot exceed ±18V.
As amplifiers of this kind are frequently used to drive small loudspeaker cabinets, the bass frequency range is rather sacrificed. Therefore a bass-boost control was inserted in the feedback loop of the amplifier, in order to overcome this problem without quality losses. The bass lift curve can reach a maximum of +16.4dB @ 50Hz. In any case, even when the bass control is rotated fully counterclockwise, the amplifier frequency response shows a gentle raising curve: +0.8dB @ 400Hz, +4.7dB @ 100Hz and +6dB @ 50Hz (referred to 1KHz).
Mar 16th, 2009
by Electronics Online.
This power supply circuit can supply high current for your electronic project. Transistor 2N3055 is the main component which will increase the current level.
| Part |
Total Qty. |
Description/Value |
| R1 |
1 |
680 Ohm 1/4 Watt Resistor |
| C1 |
1 |
20,000 – 50,000uF 20-40 Volt Capacitor |
| C2, C3 |
2 |
100uF 50 Volt Capacitor |
| C4 |
1 |
0.1uF 50 Volt Capacitor |
| C5 |
1 |
0.01uF 50 Volt Capacitor |
| D1 |
1 |
Zener Diode (See Notes) |
| Q1 |
1 |
2N3055 Or Other (See Notes) |
| T1 |
1 |
Transformer (See Notes) |
| BR1 |
1 |
Bridge Rectifier (See Notes) |
| S1 |
1 |
SPST 250 VAC 10 A Switch |
| MISC |
1 |
Case, Line Cord, Heatsink For Q1, Binding Posts For Output |
