Sunday, November 27, 2011
drewbiegs.wordpress.com
This is my old site, please check drewbiegs.wordpress.com for latest posts :)
Friday, January 15, 2010
New Blog Site...
I have moved my blog to drewbiegs@wordpress.com (will become blog.drew2gs.com). Looks like I have more features to play with than Blogger.
Tuesday, January 5, 2010
New Year updates...
Some New Year Updates
*Drew ][ TDX Card*
Now have some sample back plates and 15 PCBs have turned up :-)
*Portable GS Stereo Card*
Have moved away from the LM386 pwr amps and now using a single dual power amp TDA2822M. This was primarily to keep component count down as the dual pwr amps are actually more expensive.
I am also testing with the DS1802 dual digital pot (this provides a single IC with mute function, but doesn't remember the wiper position unike the DS1669 though its more designed for volume control). I would say I am almost there for a completed circuit and just ironing out some minor issues to avoid instability in the circuit.
It is looking like the prototype board for the GS laptop will consist of:-
The GS Laptop project have tight timescales so at the moment focus is on this rather than the Drew ][ TDX card...
Michael Mahon has been a real mentor for this project and massive thanks goes out to him.
*Drew ][ TDX Card*
Now have some sample back plates and 15 PCBs have turned up :-)
*Portable GS Stereo Card*
Have moved away from the LM386 pwr amps and now using a single dual power amp TDA2822M. This was primarily to keep component count down as the dual pwr amps are actually more expensive.
I am also testing with the DS1802 dual digital pot (this provides a single IC with mute function, but doesn't remember the wiper position unike the DS1669 though its more designed for volume control). I would say I am almost there for a completed circuit and just ironing out some minor issues to avoid instability in the circuit.
It is looking like the prototype board for the GS laptop will consist of:-
- MC14052B - DeMux
- TL082 - Op Amp
- DS1669 x 2 - Digital Pots
- TDA2822 - Dual Pwr Amp
The GS Laptop project have tight timescales so at the moment focus is on this rather than the Drew ][ TDX card...
Michael Mahon has been a real mentor for this project and massive thanks goes out to him.
Monday, December 7, 2009
TDX Laptop Stereo Card - Progressing..
***Update***
11/12/2009
Well finally hit some good headway with this tonight and have a fully working circuit with dual channels and volume control and works happily with headphones.
This uses the base of the original circuit (as per the FAQ) but removes the 2nd stage op amp and introduces 2 x LM386 power aps and 2 x DS1669 Digital Pot ICs. There are 2 push buttons that control up and down volume.
Massive thanks to Michael Mahon who has been very patient with me over the last couple of weeks :).
Still have quite a bit of work to do as I also plan to look at other ICs that might be able to simplify the design..as currently the power amp section requires 4 ICS....
7/11/2009
Well I plan to do a small run of the version 1.0 card (15 cards or so and will be offered to the CSA2 community first). The output is designed to go via power speakers. My website will get updated at some point to reflect availability :)(www.drew2gs.com).
I have stopped working on getting input functionality working, but rather have decided to focus on making a card that can fit in the portable GS that is being made by www.a2gs.com.
The portable GS will need to be able to run via headphones or un-powered internal speakers. This means I need to redesign the existing card to contain power amps. This has also made me think that once I get input working I can make a version 2.0 stereo card that has Line-out, headphone-out with vol control and Line-in/Mic-in. There is potential here to obvious make a completely slotless design.
**It was pointed out that I can get rid of the line-out and just use headphone out to connect to powered speakers**
Well tonight have had 100% success getting headphone output to work with volume control and zero distortion :). This happily worked along side the line out with no obvious issues. Was only able to test one channel as currently only have 1 potentiometer. To get it to work successfully I bypassed the 2nd OPAMP.
There is still hiss/white noise which I am not happy with until I have eliminated the bread board, but am going to continue with the current design. I will use a version 1.0 board along with a hand made board to see what it all sounds like before i start looking at layout and how to get it to a size the portable GS guys are after :).
Working breadboard (one channel powered) utilising bother lineout and headphone out.
11/12/2009
Well finally hit some good headway with this tonight and have a fully working circuit with dual channels and volume control and works happily with headphones.
This uses the base of the original circuit (as per the FAQ) but removes the 2nd stage op amp and introduces 2 x LM386 power aps and 2 x DS1669 Digital Pot ICs. There are 2 push buttons that control up and down volume.
Massive thanks to Michael Mahon who has been very patient with me over the last couple of weeks :).
Still have quite a bit of work to do as I also plan to look at other ICs that might be able to simplify the design..as currently the power amp section requires 4 ICS....
Well I plan to do a small run of the version 1.0 card (15 cards or so and will be offered to the CSA2 community first). The output is designed to go via power speakers. My website will get updated at some point to reflect availability :)(www.drew2gs.com).
I have stopped working on getting input functionality working, but rather have decided to focus on making a card that can fit in the portable GS that is being made by www.a2gs.com.
The portable GS will need to be able to run via headphones or un-powered internal speakers. This means I need to redesign the existing card to contain power amps. This has also made me think that once I get input working I can make a version 2.0 stereo card that has Line-out, headphone-out with vol control and Line-in/Mic-in. There is potential here to obvious make a completely slotless design.
**It was pointed out that I can get rid of the line-out and just use headphone out to connect to powered speakers**
Well tonight have had 100% success getting headphone output to work with volume control and zero distortion :). This happily worked along side the line out with no obvious issues. Was only able to test one channel as currently only have 1 potentiometer. To get it to work successfully I bypassed the 2nd OPAMP.
There is still hiss/white noise which I am not happy with until I have eliminated the bread board, but am going to continue with the current design. I will use a version 1.0 board along with a hand made board to see what it all sounds like before i start looking at layout and how to get it to a size the portable GS guys are after :).
Schematic with the output from the low pass filter opamp going into a LM386
Sunday, November 22, 2009
TDX Stereo Card - Prototype Complete
25th November **Update**
It seems the white noise wasn't helped by using headphones to do my testing. As soon as I used a set of powered speakers the sound seemed much much better. There is still some white noise over the right speaker but much less so than my Audio Animator. Therefore I would say card is all good for production, once i decide if i want to add input capability or not :).
24th November **Update**
Prototype was completed tonight. Didn't take long to solder together and all worked (kinda). The only issue is hiss coming from right speaker, similar to the bread board. Will investigate. Anyway some pictures are below.
****************************************************************
The card has 4 mounting holes and also a space for a connector for +5 and -5 volts to power the board without a slot. How this will get housed has not yet been decided, but at least base design can potentially be used for slotless application.
My current thoughts are now to encompass a digitiser, using info from CSA2 and also the hyperstudio audio card as an example circuit...so will be back to the drawing board once I have a working board.
Monday, November 2, 2009
TDX Stereo Sound Card - Update
6/11/09
**Update**
I have decided to wing it ;-) and have sent the latest PCB layout to have a prototype made. I should be a in a position within the next 10 days to actually make my first card.
Still awaiting quotes for back plate fabrication...:(
3/11/09
I am planning on making an audio cable similar to the Sonic Blaster one, but with only one 3.5mm jack:-
I am also looking to include a stereo phono cable similar to :-
2/11/09
Today I have been thinking about what I can really achieve in this project as a lot of things are new to me. At this point I have decided to go with a slot based design with connectors for J25 connection and audio out. This will allow the Stereo out connector to be screwed to one of the plates at the back.
One thing I don't like with the stereo card is mono sound only comes out one speaker (same as my Audio Animator, so nothing specific to the TDX), so I am planning to now put a switch to allow the mono sound to come out of both speakers giving a stereo effect if desired. This switch will be mounted on the back plate.
Work has now started on getting quotes together for PCB boards and plate manufacture while I work on the prototype card. I have had some initial quotes back. They look very promising and now just waiting for back plate fabrication quotes.
I fully plan to investigate slotless design and ADC after the initial run is completed.
**Update**
I have decided to wing it ;-) and have sent the latest PCB layout to have a prototype made. I should be a in a position within the next 10 days to actually make my first card.
Still awaiting quotes for back plate fabrication...:(
3/11/09
I am planning on making an audio cable similar to the Sonic Blaster one, but with only one 3.5mm jack:-
I am also looking to include a stereo phono cable similar to :-
These cost less than a £1 each , so it will depend on what the total cost comes to for the card.
2/11/09
Today I have been thinking about what I can really achieve in this project as a lot of things are new to me. At this point I have decided to go with a slot based design with connectors for J25 connection and audio out. This will allow the Stereo out connector to be screwed to one of the plates at the back.
One thing I don't like with the stereo card is mono sound only comes out one speaker (same as my Audio Animator, so nothing specific to the TDX), so I am planning to now put a switch to allow the mono sound to come out of both speakers giving a stereo effect if desired. This switch will be mounted on the back plate.
Work has now started on getting quotes together for PCB boards and plate manufacture while I work on the prototype card. I have had some initial quotes back. They look very promising and now just waiting for back plate fabrication quotes.
I fully plan to investigate slotless design and ADC after the initial run is completed.
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