Digiblaster

[Bryce]

Option A would add around 10€ to the price and mean that you'd need to connect it to the 5V source too.

Bryce.

[mr_lou]

30 euro + shipment would be ok for me.

But the additional PSU needed would be a drag.

Any chance we can use the CPC PSU for the Digiblaster, and then have a cable from the Digiblaster to the CPC? So that only 1 PSU is needed to power both the Digiblaster and CPC?
Would that be 32 euro then?

[Bryce]

I don't mean a separate PSU, just an inline connection between the monitor and the CPC on the 5V line.
(It would still be 30€ )

Bryce.

[CPCIak]

What do you think about using a power connection like the SD-HxC Interface's one?
So users wouldn't need further cables...

[mr_lou]

I don't mean a separate PSU, just an inline connection between the monitor and the CPC on the 5V line.
(It would still be 30€ )

Groovy! Well, I'll have me one of those then, with edge connector. 

Gimme ya paypal addy so I can transfer the funds.

[mr_lou]

What do you think about using a power connection like the SD-HxC Interface's one?
So users wouldn't need further cables...

I think that's kinda what he's going to do. It's going to be like his mouse project. Power comes from the monitor (or another PSU if you're using e.g a TV), into the Digiblaster, and then there's a wire from the Digiblaster which goes into the CPC.

[Bryce]

Hi all,
      at the weekend I finished the Digiblaster III design and built one to try out. I had intended building four of them, but I was overcome by a serious case of "stupid", which involved a) losing an entire bag of 10K resistors (no idea how I did this, but they are gone) and b) realising that the layout won't fit on the edge connector version (the board protrudes too far down)  Anyway, here's some pictures of the centronics version. I have enough material (when I find the 10K resistors) to make four of these and I will get around to making an edge connector version later this week.

So what's different between the Digiblaster II and version III ? For a start, I've added a line-in connector, so that you can feed the CPCs AY output through it so that everything comes out the one set of speakers. The Digiblaster now outputs dual-mono and the AY output remains stereo. The other change I've made was to make it REALLY linear. The original Digiblaster (and version II) used binary weighting to perform the DAC, this has several issues: For a start it means buying loads of different and uncommon value resistors. Secondly it's almost impossible to get the values correct, so that Bit 2 is exact 2x bit 1 and so on. And thirdly, the output impedance varies depending on the binary value. So instead I've used an R2R network, which solves all of these issues. The variable resistor you can see at the bottom is to balance the Digiblasters output with the AY output, so that they all have the same volume. The output signal is at line-out level, so it should be connected to a set of active stereo speakers.

Whoever wants one of the centronics ones let me know. They are 20€ plus 4€ post if you are in Europe.
I'll put the schematics and layout details on the Wiki later, for anyone who wants to build it themselves.

Bryce.

[CPCIak]

I'd like to buy one Centronics version!

[Cpcmaniaco]

And I'd like to buy one Centronics version too.

[Bryce]

Hi all,
     I got busy last night and built another 3 Digiblasters. Those who have already ordered and paid (You know who you are) should receive them within the next few days. Edge-Connector versions will take a couple more days, sorry

Bryce.

[mr_lou]

I got busy last night and built another 3 Digiblasters.

That's great news! 

Edge-Connector versions will take a couple more days, sorry

That's terrible news! 


Oh well, I'll live... Take your time, no rush.

Looking forward to hearing some feedback from some of the new Digiblaster v3 owners. 

[Bryce]

Yeah, sorry about that Mr Lou, you started the request and end up being almost the last person to get one 
On top of that I keep getting distracted by good weather, beer and football, which doesn't help progress.

Bryce.

[TFM]

Hi!

Well, the Digiblaster III seems to be a nice piece of hardware. Hope to meet one day a guy with the DIII, because I built myself the original Digiblaster long ago. Would be interresting to compare the "sound" of both versions.

BTW: In case you want to hear some samples on the Digiblaster I, II or III, you can take a look here:
http://www.colorado-boys-muenchen.de/users/futureos/files/Fraktal&StarTrek.zip

and here:
http://www.colorado-boys-muenchen.de/users/futureos/files/MegRyan.zip

In both cases your CPC needs a 512 KB RAM expansion and FutureOS, which you can get here:
http://www.FutureOS.de

Enjoy the samples...

[Bryce]

Thanks, the difference in sound between V2 and V3 is very little, the changes I made to the resistors improve the linearity and stabilised the output impedance, it also seems to have slightly boosted the bass tones a little (I built a Digiblaster II to compare them). The main difference is the through-put for the AY, which was really asking to be added. I will be adding the schematcis and layouts for V3 to the wiki when I have everything finished, so you can build one yourself and make the comparison, if you like.

Help needed:
I need some support for the edge-connector layout. Problem is I don't own a UK 6128. Can someone in possession of a UK 6128 please measure the dimension 'A' shown below on the badly drawn 6128 profile below, ie: from the desk surface to the edge connector PCB. I need to know how far down the PCB can protrude.

Thanks,
Bryce.

[CPCIak]

The Digiblaster just arrived today. Thanks a lot Bryce, I'll test it next weekend.

[Bryce]

Wow, that was fast, I only brought it to the post office yesterday at 17:00 !!

Let us know you're thoughts and opinion as soon as you've tried it out.

I assume it has arrived in one piece?

Bryce.

[Devilmarkus]

@ Bryce:
the German 664 has it's edge connectors near at bottom.
So you will have no place free under your edge connector to have PCB here.

[Devilmarkus]

The 6128 looks similar.
(Its the German one but you can see clearly the PCB under the centronics connector.)
The UK-CPC has the edge connector here.

[CPCIak]

Don't worry Bryce - I got it in one piece

Maybe you should use a flat cable plus edge connector for 464/664:
http://cpcwiki.eu/forum/index.php?action=dlattach;topic=454.0;attach=276

[Bryce]

That's the connector I use, but I will alter the layout slightly to make it similar to the Centronics version. If you check your newly acquired Digiblaster closely, you'll notice the connector is also one that was intended for a flat cable.

Bryce.

[Bryce]

Hi all,
      guess who's been a busy bastard industrious person today. Finished the edge-connector layout and produced two boards...
To the two people who ordered edge-connector versions... PM on its way.

Bryce.

[robcfg]

Hey Bryce, nice work!

May I order an edge version one?

[TFM]

Sorry for german... miss the english words...

@Bryce: Kannst Du den Drucker-Port eigentlich auch durchschleifen? Das wär mal eine Neuerung, dann muss man nicht immer umstecken.

[Bryce]

Hi TFM/FS,
       first (for others) the question asked was whether it would be possible to make a thru-connector for the printer to be connected at the same time.

Answer: Difficult, the resistors pull all the data bits low, so you would need to add an 8-way switch to physically switch from Digiblaster to Printer. 8-way switches aren't common, and 4x 2-way switches would take a lot of space, expensive and be just as much work as disconnecting the printer. I also doubt that many people still print with their CPC? But maybe I'm wrong.

Bryce.

[Bryce]

Update:

Just like the German National Football Team, I managed 4 at the weekend

And just like the English National Team, I'll be "hitting the post" some time later today

(sorry lads, just had to get that one in )

As you can see from the picture below, the Edge-connector version has a slightly different layout and is also slightly smaller. Those of you who are expecting one, they should arrive some time later this week.

Bryce.