JoaMat

don't hold it for to long, it might get old

I think it might be possible to squeeze in a digital attenuator in Mini Dynalo. ATtiny85 is in the middle of the breadboard, lots of space for it in the box. Need some 5 volt supply as well.

Right, no volume control - also the way it should be.

I said a few days ago that I’ve given up Attiny85 as controller for the digital attenuator. I’ve done some additional attempts today and it turns out to work all right. I really like that little thing. Can’t be more minimalistic..? Regarding pops/clicks I think I've to give up. Seems to be to complicated for me to solve.

Very nice indeed! And two boxes - that's the way it should be!

Got Kerry’s VolumeController to work. Wasn’t that difficult when I just figured out the output pins for the digital attenuator. Compiles much faster and uses much less memory than my firmware. Nice display, like the relay indicators!

Thanks guys. Found a post at diyAudio by Russ White. Mr. White said the problem was easily addressed by some change in the firmware. Well, I think this will be a real challenge for me…. will give it try though.

Have been struggling with controller for the digital attenuator. Finally the Arduino Pro Mini works OK, both with rotary encoder and with potentiometer. I’ve also tried the little Attiny85 but it didn’t worked with both relay banks so I’ve given that up. Power supply is to get an idea of current requirements for the attenuator. I’ve pops when relays are switching between 7/8, 15/16, 31/32, 63/64 and 127/128 “bit”. At AMB’s forum the pops are discussed and I guess I’ve to live with that??

Sort guld. Very nice.

Congratulations!

Have made some progress programming both Arduino Pro Mini and ATtiny85. My impression is that using 7 relays with 0.5 dB steps is sufficient and the eighth relay mostly contributes to more silent silence. Opinions from folks that have experience from digital attenuators are welcome.

Yes, it’s 2-layer. I think homemade inner layers is too complicated. Making vias is not that funny either. My board is a bit smaller than the original, no terminal blocks and one ground plane for the entirely board. Kevin’s board have solid inner ground planes which is preferred, but I can’t do that in my kitchen. By the way I'm retired, gives some additional time for funny things.

Relays clicking.

Excellent work you are doing with the controllers, Kerry. I’m trying to learn how to program the Arduino. Below is an Arduino UNO with an OLED and a rotating encoder. Turning the encoder - volume goes up/down. Encoder knob pushed toggles mute. If rotation while in mute the volume is changed, but takes effect first when mute is off again. Last volume value is stored in EEPROM and is called back next time controller is powered on and it starts with mute on. I don’t know if this really works - I don’t have a digital attenuator.

I used this link for programming the ATTiny with Arduino Uno. Maybe you have to change the supply voltage on Volumite so it works with the digital attenuator. Edit: Consulting MAX4820 datasheet - looks that 3.3V at Volymite should be sufficient??

Thank you. Programming – that’s my problem. I’ve to keep it simple. With ATMega328 you will have lots of opportunities – motorized pots., OLEDs, remote control etc. etc.. An AMB OLEDuino version would be great. If you just are able to program it. Excited to see what’s coming.

May I jump in and quote myself? Volumite consists of ATtiny85, potentiometer and voltage regulator. At picture above there is a ATtiny on the breadboard, power supply and potentiometer. The microprocessor is programmed and it seems that I get the correct signals to control the digital attenuator. I don't believe you can use Twisted Pear Audio's codes with Kevin's digital attenuator.

@Kerry, any good part number for the crystal Q1?

Yep, 8 bit digital attenuator is the future.

I just held the chip with one hand and with a small pliers I carefully bent the pin. After bending 30 degrees or so I took a new grip with pliers moving it a few tenths of a mm to avoid a to sharp bent. Well, try it – I did ten pieces and all successfully - maybe beginners luck…

I did consider tubing, but the min distance between pins is about the same as for those without crossed legs. As long as I don’t try to stick some test pins in there I think it’s safe.

IMO it's fairly easy to build a nice case for this board without the need for standoffs.

Happy Birthday!

One could say that the legs of BJT is shifted one step to the right. So I just bent the legs accordingly and put a pin header in the left hole and then mount the transistor with desired torque . As I do it the pin header is hold in place by the crossed leg. Solder and it’s done. Few pictures below. Hope they show how I did it. I've modified one T2 and one Blue Hawaii this way. And it works fine.

It's a test board. I like natural colored PCBs.