About the SID parts

Parts Questions
1

Just got the pcb from Mike!

Just a question again about the order list:

In the Sid module you got an Polarised Capacitor 2200 uF/25V(!).

But in the sid_V2.brd it said 1000uF/35V

If I got the 2200uF/16V is that enough? (I got the 8580 SID 9V)

Thanks!

Christoffer

2

Hi Christoffer,

I increased the capacitance to 2200 uF for people who don’t use a walladapter, but a common transformer - just to ensure that they don’t hear unwanted 50 Hz (60 Hz) AC buzz.

The 16V cap should also be ok for your 9V chip… normaly it is recommented that the maximum voltage of the cap behind a rectifier should be 2 times the RMS voltage, but the current through the circuit is so low, that this suggestion don’t have to be taken into account (IMHO)

Best Regards, Thorsten.

3

I have a commodore 128 lying around gathering dust en tiny little insects…I believe this computer has the same SID-chip, the 6581. I’m about to ask a stupid question: can I use this chip also for the SID-project?

bye

4

Hi

I think the 128 uses the MOS 8580

It apparently has a more digital sound than the C64 and runs at 9v instead of 12v see the extract below

Quoting>

The module requires a second power supply which delivers clean and stable 12V for the audio section of the 6581 chip. The current drain is below 100 mA, so the small brother of the 7812, the 78L12 can be optionally used as voltage regulator. If you plan to utilise a 8580 instead of the 6581, 9V are required instead - so replace the 78L12 by a 78L09 (or 7809…) in that case

The two caps between Pin 1/2 and 3/4 of the SID are required by the filter. The ideal values may differ with the SID version you are using, so it’s possibly a good idea not only to purchase the recommended 470 pF caps for 6581, 6.8nF caps for 8580 (which have been taken from the original schematics), but also some other pairs: 1nF, 2.2nF, 4.7nF - just to check for any better results.

The parts are spec’d on the link below

http://www.ucapps.de/mbhp/mbhp_sid_orderlist.txt

be sure to have a good read of the SID pages

http://www.ucapps.de/mbhp_sid.html

http://www.ucapps.de/midibox_sid.html

Good luck

LO

5

I think the 128 uses the MOS 8580

It apparently has a more digital sound than the C64 and runs at 9v instead of 12v

…(just by the way)  I found a MOS 6581 on my C128 Motherboard.

  • Lemonhorse