High Voltage Power Supply Unit - Kit variant
High Voltage Power Supply Unit is module intended for powering of Nixie Tubes, Magic Eye Tubes and other applications requiring high DC voltage.
Module is designed as switching DC/DC step up converter. It requires low (save) DC input voltage that is converted up to setting value with high efficiency. This concept allows to application to be powered by one low voltage source only.
Caution: This device is a source of dangerous output voltage and must be handled by adults only! The work on this device is only allowed to competent authorized persons with the proper electrical qualification!
When you are handling this device it must be always disconnected from the main power source and wait until the output voltage drops to a safe level, which should be confirmed by measuring with voltmeter!
The completed device must be placed inside of an insulating cover, which isolates contact with dangerous output voltage!
|Input Voltage (Vi):||10V to 18V DC|
|Output Voltage (Vo):||adjustable from 110V(±8V) to 180V(±3V) DC|
|Maximum Output Power:||5W (without using of switching transistor cooler)|
|Dimensions (W x D x H):||36(1.42") x 38(1.5") x 15(0.59")|
Measurement of Output Voltage while Input Voltage change (Output Voltage = 180V, Output Load = 5W).
Measurement of Output Voltage adjustment (Input Voltage = 12V, Output Load = 5W).
The Power Supply module is delivered as kit, so customer can find his own pleasure and assemble all needed components by own hands, without designing and manufacturing of the printed circuit board.
Module is based on integrated circuit MC34063. This control circuit is delivering the main functions for DC to DC step-up voltage conversion. Physically there is used the process of "slow" energy accumulation within inductor (coil) and fast releasing of accumulated energy into the capacitor.
1. A control circuit MC34063 turns on the switching transistor (Tswitch) at the beginning of the working period.
2. An electric current begins to flow through inductor (Lmain) and energy begins to accumulate in magnetic field. (Magnetic field is creating).
3. Control circuit opens the transistor after some amount of energy is accumulated in the field.
4. An electric current that created the magnetic field stops flowing through inductor and magnetic field begins degrading.
5. The time-varying magnetic field induces a voltage pulse in the coil's conductor which opposes the change in current that created it.
6. Created pulse is gradually charging the output capacitor (Cout) through the fast diode (Dfast). The Pulse height is limited by output capacitor voltage, which is gradually increased by adding charge.
7. Thus, the energy accumulated in the inductor moves into the capacitor and another working period is following (steps 1 - 6 are repeating).
8. The feedback voltage is created from output voltage value by resistor divider (R1div and R2div).
9. The maximum output voltage is limited by comparing of feedback voltage with 1.25V internal reference. If the feedback voltage exceeds the reference voltage value, the control circuit stops switching the transistor, output capacitor charging does not increase and this stops increasing of output voltage.
10. This state continues until the feedback voltage falls again below 1.25V and the control circuit resumes switching.
Note: In case module is running without load or with small load, there is possible to hear quiet sound. Frequency of this sound is not working frequency but depends on load value and is causet by output voltage regulation (points 8 and 9 - switching / not switching).
Version 1 (prototype)
Very first version realized on Printed Circuit Board (PCB). There was used axial coil, but first measurements shows problems with efficiency (60%). Heeting of coil and switching transistor was significant in this case.
Trying of several coil types shows, that overal efficiency strongly depends also on quality of used coil. Because the new radial coil was find, decision to create version 2 has been made.