Ok, I realize I'm really late to this thread, but I've just only found it going through the archives and I thought I'd pitch in, because it might help someone in the future: I spent quite a bit of time looking for inexpensive multi-channel DACs.
I have a "bargraph" project on the back burner and I wanted to drive 8-12 IN-13 tubes. The best solution I could find was a ROHM BU2501FV DAC. It's a 12-channel DAC with rail-to-rail output capability, driven via a serial shift-register-like interface. Seems perfect for this kind of application. I was planning to use it with transistors to drive the tubes. I got the chips from RS Components and they were not overly expensive. The BU2500FV is 5V, BU2501FV is 3V. The nice thing is that it also has a VrefL pin that allows you to supply a lower reference voltage for the DAC. I was planning to supply it with a diode drop, to offset the B-E voltage of the driver transistors, which would give me a lot of room to work with. You might also want to look at BH2221FV. --J. On 4 gru 2013, at 00:04, Jon <[email protected]> wrote: > > On Tuesday, December 3, 2013 2:24:03 AM UTC, Chill4844 wrote: > I am attempting to use an Arduino in conjunction with a TLC5940 to drive an > array of IN-9's (And not kill myself or blow anything up) the problem being > if i understand it right (which I probably don't) is that instead of a > positive PWM out the arduino the TLC5940 works by sinking the current on the > cathode side. I don't think i can use this with my standard mpsa42 (and I'm > not going to attempt anything until i get some advice) I do have some > mpsa92's available. > > I don't think you want the PWM capability of this chip for IN9. For what > you're trying to do, take a look at the TLC5628 which is an 8 channel DAC > with a simple 4 wire interface to the microcontroller. Hook the output of > each DAC channel up to the simple MPSA42 current sinks per Jeff's paper, and > that's all you need. You can manage around the Vbe offset in software to keep > the hardware simple. That's the technology which sits behind this: > http://youtu.be/mQ1567EFCY0 > > Grahame rolled his own version and documented it here > (http://www.sgitheach.org.uk/ss.html) including a full schematic. > > BTW, IN9 are very variable and suffer a lot from cathode poisoning. To get an > array of them to perform consistently well and in a uniform way is going to > take quite some tube selection and conditioning. IN13 may be a better bet, > though they are rather dim to my eye. > > Cheers, > > Jon. > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send an email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/ec596498-2b0c-4a67-99f8-836eb94ef88a%40googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/A0393D25-CE1C-412B-9661-DC97FD40D52D%40gmail.com. For more options, visit https://groups.google.com/groups/opt_out.
