/tilted/

No, it would absolutely affect the whole circuit. If the 7805 were faulty or wired incorrectly, (say, it causes a short or near short) the Lm317 would be desperately "trying" to feed the full regulated voltage to a shorted 7805. In this case, to compensate for extreme voltage drop, more current is allowed through. This soon becomes an extreme example of ye old Ohms Law: I=V/R if R (resistance) is very low, I is very high. if R is zero (or a real world version of zero ;) ), then I runs off in the general direction of infinity. of course, R won't reach zero with a correctly working 317, hence your voltage pulled down to 2-3v, not 0v.

I've been pondering this one a bit. I found a very brief mention of a 32x2 character LCD here: http://www.myke.com/lcd.htm this would result in a (64x2) LCD. You'd get the full width of 55x2, with extra space besides, and slightly less cavernous than (80x2). I have not been able to find 32x2 LCDs for SALE however. Even a 32x2 display would not solve the issue of space between banks of 4 faders, as there would still be the ends of the LCD to hide (the non-viewable parts of the LCD). Mostly related n00b question: Is it (relatively) easy to change the character spacing in fader and Vpot modes? If I end up using a 40x2 display, it would be nice to at least use all of it... Ta.

This is AWESOME! TK you are the best!

Hi. I may be way out of line here, but from my experience, opamps such as the TL074 work much better with higher supply rails. You can absolutely use +/-5V rails, but be aware the noise and distortion figures may be compromised. Good luck! Matt

I believe the STEC16 series has the common on one side rather than in the centre.

Ah HA! Perhaps the 78L05 was wired incorrectly? I think the pinout on those is different to the full-size 7805 version...

Perhaps. I would double check the resistance of R1. It should be around 220 ohms. If you have the means, I'd even suggest measuring R1 and P1 with a meter to be sure. (Those bands can be tricky - Red-Red-Brown-other, or Red-Red-Black-Black-other while were on the subject... ;) ) If the voltage changes when you adjust P1, then the reg is (sort of) working, but there seems to be a problem in the resistor network.

I assume, through all this, that you have tried adjusting the P1 pot? By my calculations, the setting of the pot is quite likely around 300 ohms.

I'm not sure where you are measuring the 3v "out of" the 7805, But according to the spec sheet, the 7805 will drop out if it sees less than 7.2 volts. Also, carefully check the adjustment resistors R1 and P1 (near LM341), as these will determine your output voltage directly. Ensure they are in the correct orientation (ie that R1 is conn. to "out" and "adj" and that P1 is conn. to "adj" and ground) if these are in reversed positions, you might well get a lower output than desired. If the P1 is not wired correctly, you may well get a voltage as low as 1.2V! (This would be a short between ADJ and GND). Also, Does the "power" LED turn on? I would think not, as it is derived from the 7805, which should be dropping out... Also, your LM317 will get hot as a result of dissipating excess voltage as heat. This is why it is vital that the adjustment components are correctly oriented. If your battery voltage is (close to) 18v, and your regulator is adjusted to 3v, the regulator has to get rid of 15 volts, which is not impossible, but is a challenge ;). If you can still touch the reg without burning yourself, it is no real cause for concern.

It sounds to me like you may have your regulator and diode wired backward. Double check your wiring against the schematic . Also measure the battery voltage with the batteries out of circuit. First alone (9v each) and also in series (18v total) if you get significantly less than this, you may have a problem. I would recommend using a PSU for this EVENTUALLY, but I would fault-find using batteries first (as they are less likely to burn your house down ;)

You say you have two fans, one for inlet, one for exhaust? Does this mean you have some nifty heat tunnel design? If so, would it be possible to place the fan or fans in the centre of the duct? I also saw mention of peltier effect devices... these take a fair whack of power, but could be helpful...?

Are you sure you are talking about the right pin? According to the schematic diagram for the DOUT, the pins, running left to right, are: [tt]Reg 1 Reg 2 D07,D06,D05,D04,D03,D02,D01,D00 || D07,D06,D05,D04,D03,D02,D01,D00 P07,P06,P05,P04,P03,P02,P01,P00 || P15,P14,P13,P12,P11,P10,P09,P08[/tt] So yes, this is exactly backwards, you've done nothing wrong, except you've counted the pins left-to-right.

Your C64 will absolutely have a 6581 chip. The revision number could be anything between R2 and R4 (from memory R1s are very rare I think, but it might be an R1). Regarding the chips and cases thing, there is a grey area: All of the original dark beige cases use 6581. All of the 8580 chips will be found in the newer cases, designation C64C, C64E or C64G. Notice the different phrasing here because: Not all of the C64C,E,G cases have 8580 chips. You can be virtually assured that the newer style case will contain either an 8580 chip, or a 6581 R4 chip, these chips have better (and more consistant) filter performance, the 8580 having a slightly better Signal to Noise ratio (in the region of 90dB, rather than >76dB, in the 6581 R4). I've heard of various means of finding the 8580s (The Prophet64 page suggests that 8580 boxes have the old school graphical symbols on top of the keys, as opposed to the front, but then suggests this is not a definite rule). Unfortunately there is no way to know before your 64 arrives. Fortunately, MBSID is compatible with any of these chips, so you can just upgrade your MBSID with additional chips!! ;) Have fun!

Indeed. Melbourne. -Mind you, until I clear a little space, and make a little time, I wouldn't say I'm a "builder" yet... ;) more of a dreamer, although I am doing a little design work working on integrating the DIN, DOUT and interfacing componentry required for a MBSID into a 3U front panel PCB (using expressPCB), and figuring out a matching panel (using schaeffer).

I just saw a SID 8580 sell on eBay for (drumroll)... 25.50 Euro! Just the chip, no mainboard, PSU or anything else. -No guarantee it works, either!! So far I've bought 10 C64s, at an average of $10-30 AU (6-18 Euro) generally with about 2.5 joysticks, a swag of games (and gamez), tape drive, disk drive, psu, anything else the seller wanted to throw away... Am I just lucky? Is it possible the 25.50 goes toward the cost of storing all that other garbage? I know I've now got a storage shed with a heap of graveyard parts. Has anyone else seen madness on eBay?

Very nice box. How thick is the plastic? What type of plastic? If you plan to paint the outside, perhaps you could reinforce the inside of the box with some fibreglass resin and webbing. Of course, you could still do this if you plan to keep it clear, but you'd want to be super clean and neat. Then you could fill the thing up with LEDs and throw on a couple of photo theremins and/or ribbon controllers... Whoa! I want one! What sort of candy box was it again?

Is it possible that you have reached the PIC's "100,000 erase/write cycle Enhanced FLASH program memory typical" physical limit? I seriously doubt this, of course. It's not ye olde "RAM between 0x60-0x7f is not directly accessible" issue?

OK, so the chip is in a non-DIL package. This puts it on a par for soldering difficulty with the YMF262 or YAC512 used in the OPL3 module. I think the TI chip would be more useful as a seperate volume control module, as I recognise that not everyone is likely to want/need this control. The TI chip is sold by DigiKey (Part no. PGA4311U-ND) for around US$10. I'm certainly not saying this chip is the only way to do this, but it is a means to an end. So, stryd_one, I'm a little set aback by your reply. Is there already mention anywhere here of using an LFO to directly modulate the frequency of another LFO? I haven't found any mention in the 2+ years I've been reading the site. Have I managed to miss something? /tilted/

Hi. Regarding a question on volume control: It seems TI make a 4 channel serial-controlled DCA chip called PGA4311. It has a seperate +/-5V analog supply, and +5V digital supply, and a feature that allows for automatic zero-crossing detection (to remove volume change glitches). I'm not sure of the resolution, but it seems to be 8-bit (hooray for 8-bit!!) or possibly higher (also good ;)) It seems it can also be daisy-chained (for the new 4x stereo SIDsynth). I imagine the best feature here would be that we could choose a smooth (glitch free) volume envelope, realised in the analog domain but controlled digitally, but also retain the option of glitching the SID's 4-bit VCA register 8)... On a seperate topic (ie the wishlist) would it be possible to set up modulation of LFOs by LFOs or ENVs? I imagine there is AM available by selecting multiple sources, but is LFO FM available as well? ie: LFO1 + ENV1 = FM for LFO2 (Ladies and Gentlemen, right this way to hear a lot of very weird sounds...) TK? what do you think? /tilted/ P.S. here's the chip: http://focus.ti.com/lit/ds/symlink/pga4311.pdf