Switching power supply

5V to isolated 5V at 20mA converter by MAX635

When we need a constant voltage 5V at the current about 20mA, by there are power supply source voltage about 4V to 6V.
In this circuit, We use the MAX635 IC number is the main equipment, that acts as Preset/Adjustable Output CMOS Inverting Switching Regulators.
At pin A, a negative output dc-dc converter generates a -5V.
First, a negative output voltage dc-dc converter generates a -5V output at pin A.
Then, the primary of the transformer (T1) must fly back to a diode drop more negative than -5V.
If T1 has a tightly coupled 1:1 turns ratio (270uH), there will be a 5V positive voltage at diode across the secondary ‘s T1.
The 1N5817 rectifies this secondary voltage to generate an isolated 5V output.
The isolated output is not fully regulated since only -5V at point A is controlled by the IC1.

Be the first to comment - What do you think? Posted by admin - March 28, 2012 at 6:13 am

Categories: DC converter, Switching power supply Tags: 5v dual dc converter, isolated dc to dc converter

Step down voltage converter 5v with transistor BC337

The circuit decreases the size voltage or Stepdown Voltage converter circuit be dc regulated circuit model switching converter. The that make voltage output there is the size voltage a little more input at feed give with the circuit. From circuit picture will decrease volt 6-18V from be left 5V. It give current get 100mA.

When feed volt give with transistor circuit Q1 and Q2 the connection is astable multi vibrator. Will do frequency production comes out at a collector pin of Q2 and transmit come to at a B pin of Q3. By Q3 perform like with switch wait for close-open the circuit for control to give Q4 work. When base pin of Q4 have voltage bias make Q4 work. The C3 perform charge by change the way coil L1 make output have voltage increase continually. But if be valuable 5V more than bear fruit make Q5 work. Because have voltage come to bias at B pin by change the way ZD1 switch off work because of volt at a B pin of Q1 be 0V. The circuit then stop to produce the frequency comes out. Then make Q4 stop work with. When Q4 stop work then have no Vbias give Q5 then stop work thus Q1 then can work again and work character repeated as like this before. But there are many speeds then make output that appear can come out 5V all the time.

Be the first to comment - What do you think? Posted by admin - May 26, 2010 at 10:11 pm

Categories: Switching power supply Tags: BC337, step down regulator, switching power supply 5V

Control signal Automatic Fader by LF351

This be Control signal Automatic Fader circuit , help fine decorate or control sound signal tallly or low follow want. In model the automatic convenient for the system electricity guitar , side sound of music work. By this circuit uses FET , then have tall rapidity , there is the crazy low and use IC op-amp model FET , number LF351. Then have disturb lower. The S1 for fine the pitch High or Low get, and have fining decorates the pitch done to a turn VR1,VR2 you can the detail adds in the circuit.