Sammich SID Power Supply Queries

[orange_hand]

Hi Guys,

I have almost finished soldering the PCB's of the sammichSID and I will shortly perform the voltage testing. I have got the following questions regarding the power supply.

a) I have planned to use a 12V regulated power supply and I wonder how the polarity has to be ? Is the center positive or negative ?

b) I will use 8580er SID's and I suppose that the 12 V power adapter is ok, isn't it ? I assume that the 12 V are broken down on the voltage regulator and if the jumper is set to the default position, it should work, shouldn't it ?

c) Is the following power adaptor sufficient with the 500mA (Power Adaptor 12V / 500mA) or better this one with 1,7 A with 12 V (12 V / 1,7 A)?

I appreciate your answers !

Cheers

orange

Edited May 2, 2011 by orange_hand

[Wilba]

a) Polarity doesn't matter if you are NOT bypassing the bridge rectifier via headers JBP. However, if you are using a regulated DC power supply that is tip positive, you can optionally bypass the bridge rectifier (like you must for 6581 use) so you get 12V DC going into the 9V regulator.

b) 12V is OK. I use either a 12V AC 500mA or a regulated 12V DC. It should work fine.

c) Of those two choices, I would not choose the 2nd one because it is switchmode. The 1st one will work and is preferred because it is regulated and appears not to be switchmode. Switchmode power supplies typically have an input voltage range (like 100V-240V) and aren't so chunky. Also it's confirmed "linear" in the questions tab on that page. You might need to use shunts in JBP as mentioned above, but probably won't... 12V - 1.2V (drop of 2 diodes in brige) = 10.8 V, should be enough for 7809. YMMV.

Please update the wiki with a link to this one if it works well for you: http://www.midibox.org/dokuwiki/sammichsid

[orange_hand]

Thanks Wilba !

Cheers

orange

[Shiftone]

Bumping this thread rather than starting another to add some questions of my own.

I've got my Sammich order in so I'm looking for PSU options in the UK as well.

First @ orange_hand - did you go with that 500ma Maplin PSU and if so how did it work out?

@ Wilba and anyone else that can help.

1. Is 500ma really enough or is it much better to try and find a 1000ma PSU (I'll be using stock LEDs and LCD)

2. Can someone comment on these PSU

a) http://www.buythis.co.uk/pdf/5965.pdf

(http://www.buythis.co.uk/open_product.asp?pid=5965&catid=173&offset=48&Orderby=)

I can't tell if that is linear or not.

b) http://www.buythis.co.uk/pdf/4927.pdf

(http://www.buythis.co.uk/open_product.asp?pid=4927&catid=173&offset=0&Orderby=)

This one definitely is linear but at 500ma

c) http://www.buythis.co.uk/open_product.asp?pid=4928&catid=173&offset=&mid=73

this is switchmode but regulated and the guy at the end of the phone says it should be a very clean supply...

anyway - take a look and see what you think.

EDIT

boom and we have a winner;

http://uk.farnell.com/jsp/displayProduct.jsp?sku=1176265&CMP=e-2072-00001000&gross_price=true

order code - 1176265

can someone verify this is indeed 12v 1a regulated linear.

Edited February 8, 2012 by Shiftone

[orange_hand]

yes, the DC 12V / 500mA as stated above is working fine, no issues at all !