Archive for August, 2005

TL494- Power supply for VFD

Wednesday, August 31st, 2005

Typically in self made small hardware (DIY), power from mains transformed and rectified using simple wall “cube". But this cube produces typically 12V. A bit too low for VFD. If I would like to use some higher voltage cube for 25V it will be hard to find, and to much power will be dissipated in […]

TL494 - magic chip, Part 6

Tuesday, August 30th, 2005

While testing this device, do not overload, do not load asymmetrically. For checking your system, remove nixie and load secondary winding of transformer with simple resistor.

Download small (~500kb XVid AVI): with oscillograms. And now take a note, that on the “drain" oscillogram you see other phase pulses. Even when mosfet if in off stage, […]

TL494 - magic chip, Part 5

Monday, August 29th, 2005

Everything is working with simple passive mosfet drive. But if we increase switching frequency or place powerful mosfet (or even several mosfets)? There is no load in gate circuit, but there is gate capacitance. And if we need fast switching we must charge and discharge gate very quickly. With passive drive there are limitations. […]

TL494 - magic chip, Part 4

Saturday, August 27th, 2005

Now let’s make some high voltage! As the schematics is done on the breadboard, I can't produce high power application. This is because of very long wires used in the experiment. Also there is no any heat sink on the power mosfets. Connect transformer to the output stage according this schematics:

Push-pull load
The primary windings of […]

TL494 - magic chip, Part 3

Friday, August 26th, 2005

the output of TL494 is quite weak, and we want more power. So we need some powerful transistors attached. The most easy to use (and very easy to get- from old computer motherboards) are n-channel power mosfets. We must invert output of the TL494 because if we connect n-channel mosfet to output, in shut-down stage […]

TL494 - magic chip, Part 2

Thursday, August 25th, 2005

Now let’s speak about the pins.
GND (pin 7) and Vcc (pin 12) are usual power pins. Max Vcc is about 40V.
RT (pin 6) and CT (pin 5) are used for setting clock (1 … 300kHz). The frequency of the clock is calculated using table from data sheet and changing resistor (1.8 … 500 kΩ) and […]

TL494 - magic chip

Tuesday, August 23rd, 2005

From time to time, in newsgroups, in www forums and in www pages, people speak about converting DC to DC, or DC to AC, charge-pumping, building inverters (step up, step down converters) for various devices. From high power car audio amp to handheld stazer. There are lots of schematics (especially in Russian web) using simple […]


Hey.lt - Interneto reitingai, lankomumo statistika, lankytojų skaitliukai

Place for rent.