June 14th, 2010
Small and very useful circuit, Can be built on a veroboard
Volt regulators such as the LM708, and LM317 series (and others) sometimes need to provide a little bit more current then they actually can handle. If that is the case, this little circuit can help out. A power transistor such as the 2N3772 or similar can be used.
The power transistor is used to boost the extra needed current above the maximum allowable current provided via the regulator.
Current up to 1500mA(1.5amp) will flow through the regulator, anything above that makes the regulator conduct and adding the extra needed current to the output load. It is no problem stacking power transistors for even more current. (see diagram). Both regulator and power transistor must be mounted on an adequate heat sink. …
Source Link :
http://www.extremecircuits.net/2009/08/ampere-or-current-booster-circuit.html
Posted by admin,
in High Current supply
June 5th, 2010
Many discrete and ICs need bipolar (dual or ± V) supplies. This can be easily accomplished with two three-terminal regulators, as illustrated in figure. Opposite-phase ac is provided by the transformer’s secondary and a grounded center tap. The single full-wave bridge converts these into positive and negative dc voltages (with respect to the grounded center tap). Filtering (with respect to ground) is provided by capacitors C1 and C2.
The LM 340 provides regulation of the positive voltage, while the LM 320 regulates the negative voltage. It is very important to mention here that LM 320 has a different pin configuration than the LM 340. The case of the LM 320 is not ground. So care is to be taken while mounting the negative regulator.
Read more: http://www.circuitstoday.com/category/voltage-regulators
Posted by admin,
in dc voltage regulator
June 4th, 2010
This circuit can do by begin from feed house electricity AC 220 volt 50HZ. The T1 perform modify AC Volt 220V from reduce to 30V from that time Diode D1-D4 perform rectifier to the direct current. By have R1 and R2 limit the trend and C1 perform filter voltage the electricity smoothly. It have ZD1 and ZD2 build serial for perform fine dc voltage to +15V and -15V follow the number of Zener diode.
