This is an isolated DC to DC Converter circuit in digital. In using a digital measurement circuit to connecting with other circuits.
If the primary voltage is 5 V, but you want a higher voltage between 9V to 12V.
This circuit may solve your problem!
It can converter a DC 5V input into DC 7.5V to 12V output at 50mA current.
Important! it is an isolated style makes a good performance.
They include a few parts, a 555 timer, small transformer, Zener Diode, and more in a simple circuit.
It may help you.
How it works
Circuit diagram of 555 DC converter for digital
On circuit consist of an astable Multivibrators using a 555 timer. They will control the power supply is on and off. To drives a transformer-T1 through the transistor Q1-BC547.
The output voltage of the secondary coil is rectified by D4 (in half-wave). And filtered with the capacitor C3. Then there is the Zener diode-ZD1 as act regulated voltage.
Warning: Do not use power supply over 15V because of IC1 get damaged.
Transformer-T1 It is a 1:1 ratio pattern. You can look at these transformers in many using. For example, To control an SCR and a small radio transformer, etc.
Each type of transformer is suitable for different frequencies and pulse width.
SCR transformer is suitable for a frequency of 100 kHz.
Audio frequency transformers, as well as approximately 0.5 to 40 Hz.
VR1 and VR2 To adjust the frequency and pulse width of the output oscillator.
Then, look at the Figure below. The frequency waveform includes two-time width.
Charging Time is controlled by VR1, R1, and C1.
DisCharged Time is controlled by VR2, R2, and C1.
While Diodes D1, D2 set a direction of the current each time.
The frequency of the circuit can get by:
F = 1/[0.7C1(VR1+VR2+R1+R2)] = Hz
How to find a frequency of Output DC pulse of 555 oscillator
Zener diode ZD1 To set the output voltage. For example, 7.5V, 9V, 12V max.
This is Simple Doubler Voltage circuit, from voltage 12VDC to be 24VDC. Use the IC highly popular number, a NE555 timer. And other a few pieces of devices too.
DC doubler voltage 12V to 24V using NE555
It can give current get about 10mA-20mA. The circuit requires a low current and unstable.
The Circuit Principle works
When using Volt input 12VDC give with the circuit will touch filter current smoothly with increasingly.
The capacitors C5 give with IC1. The resistor R1, R2, and capacitors C1.
Which builds the circuit model astable multi-vibrator Square wave generator. At the frequency of about 2KHz comes out the way pin 3 of IC1.
By having capacitors C3, C4 diode D1, and D2. Which build be boost up voltage x 2.
Which will increase the voltage level at the output in the direct current about 24VDC. Or 2 times of the level Voltage input.
Sometimes, we want to test the circuits require -5V negative power supply. But we have only the 9V battery.
How to change 9V battery to -5V. Sound good?
Let me explain why this circuit can do?
Look in the circuit
Like the above circuits, NE555 runs a square wave at the output about 6V.
When the output is a positive pulse. Then, C2 charges the voltage through D1 to ground.
And if the pulse is negative. The capacitor C2 will discharge through diode D1 and capacitor C3.
This we get negative voltage is about-6V. And there is Zener diose to keep a stable voltage, -5V. With output current approximately 12mA max.
Negative supply voltage low current
we have an AC adapter for various electronic circuit experiments. But it is a single power supply only positive voltage.
Imagine your circuit requires a negative voltage supply too.
How do this case?
This circuit is an answer. Why?
It can convert the positive voltage from the AC adapter to the negative output.
Look: in the circuit.
Of course, we use IC1-555 like above circuits with R1, R2, and C1. They are A Stable Multi Vibrator circuit.
And its output is a square wave. It is a positive signal pulse frequency of 2.3 kHz output pin 3 of IC1.
And C3 and D1 connected to the CLAMP circuit. They serve to a positive pulse to a negative pulse signal.
The D2 and C3 act negative pulse signal are converted direct current (DCV) electrical signals in negative. So, the output voltage to a negative DC electrical.
I like to try different circuits by using an adapter as a power source.
But it has some disadvantages. Imagine we learn about 741 op-amp works.
We cannot use that adapter. Because the op-amps require a three-terminal power supply, positive and negative and ground.
I want you to try this circuit below.
Although, It gives a low current of power, lower than 10mA.
Let me explain you.
The NE555 in a stable multivibrator circuit produces a frequency rectangular wave about 100 Hz out of pin 3.
This Pulse signal passes C3 and C4 before to rectifies to DC voltage. They have both positive and negative, +9V and -9V.
Positive power supply will work with the rectifier D1 and D2. When a positive signal to be via D2 to the output.
And filtered by C5 to filter the voltage to smooth again. If there is a negative signal, D1 will pass it to the ground.
In contrast, the negative part, Both D3 and D4 the rectifier. When a negative signal to the output signal to be via D3. And will be filtered from C6 to smooth again. And D4 will a positive signal to ground.
Note: These circuits worked well as the video below.
