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Author Topic: 5V to 12V  (Read 3495 times)
VideopacBelgium
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« on: January 31, 2013, 03:26:07 PM »

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
« Last Edit: January 31, 2013, 03:31:12 PM by VideopacBelgium » Logged

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Rene_G7400
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« Reply #1 on: January 31, 2013, 04:29:29 PM »

The Texas Instruments datasheet of the TL497A shows some circuits.
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VideopacBelgium
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« Reply #2 on: January 31, 2013, 05:36:54 PM »

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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« Reply #3 on: January 31, 2013, 09:38:26 PM »

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
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« Reply #4 on: January 31, 2013, 10:12:38 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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« Reply #5 on: January 31, 2013, 10:16:50 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.

This would be usable:

http://www.conrad.nl/ce/nl/product/154171/DCDC-converter-TMA-serie-1-watt-SIL-7-TracoPower-TMA-0512Sin10-5-VDC-out-12-VDC-80-mA-1-W/?ref=category&rtl=reco_category&rb=1

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« Reply #6 on: January 31, 2013, 10:20:51 PM »

Oh, and by the way..  Smiley

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')
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VideopacBelgium
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« Reply #7 on: January 31, 2013, 10:25:58 PM »

Oh, and by the way..  Smiley

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
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« Reply #8 on: February 15, 2013, 07:45:29 AM »

Did you get this working ?
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VideopacBelgium
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« Reply #9 on: February 15, 2013, 12:38:53 PM »

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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« Reply #10 on: February 15, 2013, 01:07:00 PM »

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