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5V to 12V

Started by VideopacBelgium, January 31, 2013, 03:26:07 PM

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VideopacBelgium

Hi!

For switching my TV on RGB mod, I would like to build a circuit based on the TL497 IC.
Convert the pin 5V of the SCART from my PSone to 12V.
I can't find a complete schema on the web.
Can anybody help me?
Thanks a lot
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Rene_G7400

The Texas Instruments datasheet of the TL497A shows some circuits.

VideopacBelgium

Yes but no value of elements are indicated, all elements must be calculated. Sorry but I don't understand the formules. I didn't find a schema with the correct values for my circuit 12v.
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gertk

You could also do something simpler like a voltage doubler or tripler.
Even with a humble 555 you can already do this.

http://www.talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.html#10a

What kind of current does it has to deliver at 12 Volts ?

There are also ready to use DC-DC converters, 5 Volt in, 12 Volt out, some can do this fully isolated.

Conrad has this for 7 Euros:

http://www.conrad.nl/ce/nl/product/156737/DCDC-converter-2W-SIM2-0512S-SIL7
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VideopacBelgium

Quote from: gertk on January 31, 2013, 09:38:26 PM

What kind of current does it has to deliver at 12 Volts ?


I need 12v for switching the RGB input.
I expect I need 20mA at 12V.
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gertk

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gertk

Oh, and by the way..  :)

The 12 Volt on the Scart input is to switch the TV over to AV input, the RGB switch (or 'fast blanking') needs something between 0,75 and 1 Volt but is terminated inside with 75 ohm. Most newer TV's swith over to AV with only 5 to 6 Volts already but they will be in 16:9 mode (so called 'wide screen signalling')
>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<

VideopacBelgium

Quote from: gertk on January 31, 2013, 10:20:51 PM
Oh, and by the way..  :)

The 12 Volt on the Scart input is to switch the TV over to AV input, the RGB switch (or 'fast blanking') needs something between 0,75 and 1 Volt but is terminated inside with 75 ohm. Most newer TV's swith over to AV with only 5 to 6 Volts already but they will be in 16:9 mode (so called 'wide screen signalling')

Yes, this is the problem I have.
My Tv switches to RVB but in 16:9 mode.
I'll buy this DC/DC converter at Conrad.fr
Thanks a lot for your help
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gertk

Did you get this working ?
>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<

VideopacBelgium

Shipping charges for only 1 item are expensive.
I'll go to the Conrad Shop at Lille (FR) soon. (25km between this Conrad Shop and my home.)
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gertk

Yes, even RS components charges for shipping now.:-(
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