mookie

My 1o'clock code sin't too bad, but with all the new stuff I'm having to learn with electronics my brain is aching. Thanks for pointing me in the right direction. I'd overlooked the forum with Northenlightsx thread in it and it appears to be just what I need. Sorry for posting in the wrong forum with this thread. Anyway, back to work. Hopefully the next parcel from rapid turns up in the next few hours

Okay. First lesson, don't draw schematics at half one in the morning. 1. Firstly the input is using a 12v centre tapped transformer, that was my reason for using two rectifiers. One will have a 12vac input and the other a 6vac. However with your further remarks I've realised that I'm trying to feed the regulator a value too close to the output. However that can easily be fixed by changing to an 18vac transformer, again centre tapped to give two 9vac windings. (which is handy as there is one sat next to me. 2. It's late. I meant 7812 The seperate grounds thing. As I've been typing this i'm starting to suspect that that with tapping off the two windings the two grounds will be at different potentials so there is the possibility of some very nasty noises. Ah well. I guess voltage divider is the way to go. Probably simpler too. I'll have another go and get back after I've had some sleep. Thankyou very much nILS. John

I hope I'm not getting peoples back up. I have a habit of thinking out loud and I'm trying to learn so much I occasionally need to post a question as much for the answer as to arrange my thoughts. Thanks for all the help so far...

Hopefully I'm not going to continue to show my ignorance but as some people pointed out in a previous thread I'd made a bit of a misjudgement with regards to my choice of PSU. As a result I've gone back to the drawing board and had an attempt at sketching up a possible PSU. I'm posting the simple schematic here in the hope that someone would be able to check my choice of values as I'm still pretty new at this. The ceramic values I got from the regulator datasheet and the main electrolytic from the guide on diyaudio and the optimised PSU schematic (they seemed to match so I thought it would be a good starting point). Also, is it a better idea to rectify and filter the two voltages seperatly as I planned, or do I gain nothing and would it be more straightforward to rectify once and use a voltage divider to get the two power rails I need. Thankyou for your patience

It's smashes board and I believ its a revision 5. The contacts I'm on about are actually covered byt the pull up resistors once they're installed. Hoever, I seem to remember reading a post somewhere along the line that suggested the board was designed to take either a single resistor array or sets of individual resistors. I'm starting to think that they can be safely ignored, but I'm very curious.

You know what, you're right. I didn't even think about it, I was aware of the problems of a switching supply, but one glance and it's pretty obvious. Not to worry, the original query still stands, it just means I'll have to put together a different supply. Not a problem I've got a few lumps of iron knocking around

I'm currently in the process of stuffing the DIN board for a MIDIbox SID and I'm slightly confused by the layout. I'm just a little baffled by the row of contacts that appear to sit below the top row of resistors and are connected to four of each of the switches. Would someone please enlighten my, or possibly make me feel slightly foolish for not realising.

Has anyone got a uk source for these. I've not been able to find anything suitable at Rapid or Farnell.

Thankyou very much. I had a feeling that was the case. Would it be the case then that I can drop BR1 and C9 and feed the power in where C9 was.

I hope I'm not covering old ground with this post but after two days reading and note taking I'm left with one more thing (i hope) I need to get straight. I'm looking to use a PSU salvaged from a DVD player. The PSU has regulated outputs at +5v and +12v. The 5v supply is straightforward and following the documentation for the optomised PSU I can see quite clearly how to feed it into the various modules. My confusion arises from the power feed into the SID moduless. I suspected I would be able to make a similar arrangement to the core module and bypass the rectifier and C9. However, reading the info suggests I would be better off ignoring that section and just feed the DC input into the rectifier, but to do that it seems to be suggested that I would need to supply 14v. Is this to compensate for any voltage loss through the rectifier (which as I'm typing this I'm beginning to think would be 1.4v which starts to make sense) but given I'm using an 8580 which only requires 9v would that mean I can carry on and supply the module with 12v. Please excuse the rambling, due in no small part to me still trying to organise all the information I've been taking in in the last couple of days and my own limited knowledge of electronics. Thanks in advance