Variable Power Supply 1.2 to 55 Volts 3 Ampere
Posted On Wednesday, June 23, 2010 at at 9:33 AM by OwnerI was looking to get a 12 volts DC-DC converter for my 7 " LCD as i don't want to power it directly from battery.
Here is a nice Switching mode Regulator LM2576 series IC from National Semiconductor, I found it is such a good regulator according to DS:
The LM2576 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving 3A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V, and an adjustable output version.
here is the schematics:
In local market i could not find LM2576 (12V), only Adj. version is available so i decided to go with that one. I adjusted R2 preset for 12 volts as per my need.
Features
- 3.3V, 5V, 12V, 15V, and adjustable output versions
- Adjustable version output voltage range,
- 1.23V to 37V (57V for HV version) ±4% max over line and load conditions
- Guaranteed 3A output current
- Wide input voltage range, 40V up to 60V for
- HV version
- Requires only 4 external components
- 52 kHz fixed frequency internal oscillator
- TTL shutdown capability, low power standby mode
- High efficiency
- Uses readily available standard inductors
- Thermal shutdown and current limit protection
- Adjustable version output voltage range,
- 1.23V to 37V (57V for HV version) ±4% max over line and load conditions
- Guaranteed 3A output current
- Wide input voltage range, 40V up to 60V for
- HV version
- Requires only 4 external components
- 52 kHz fixed frequency internal oscillator
- TTL shutdown capability, low power standby mode
- High efficiency
- Uses readily available standard inductors
- Thermal shutdown and current limit protection
High Gain Mic Pre Amplifier
The best and cheap Pre-Amp circuit to make Microphone more sensitive to pick voice, although I had made one already but thought it worth try as it has nice gain around 100 as the author stated with a new chip TL071 which is low voltage high gain amplifier IC.
A little modification I made as you see some extra components are basically power supply using regulator chip LM7809 as I need it to run with 12V DC. This stand alone 9V regulator can be found here...
Schematics:
Finished Circuit :
These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V, and an adjustable output version. DOE Level VI