With relation to the OPA 549 gainclone thread that I started lately I also started development of pre amp based on PIC mcu and PGA.
I decided to build two version of the pre amp.'
First simple version build around PIC16F876A and PGA2310, having four input selector relays through ULN2803, an output buffer around OPA2314/OPA2107 or LM4562, a 20x2 LCD five butttons for up, down, mute, signal switching and power buttons and an IR based controller. One PCB of about 5.2x4.5 inches and an output relay to prevent power off thump
Second version is a high end one build around PIC16F877A, PGA2310, four input signal switching through ULN2803, input and output buffers on PGA, input buffers around OPA2134/OPA2107/LM4562 and output buffers around OPA627, five buttons like simple version, I.R, Rotary encoder, 20x4 VFD, and extension capability to six channel (another two) PGA2310 or a bass-treble control around AD5204/6. Three PCBs one for controller, one for analog section and one for the VFD and buttons, also an output mute relay to prevent power of thump.
As PCB fabricating has never been easier for me so I got two boards each.
What is left is an eternal wait for ICD2 to arrive from USA, to burn the mcu, software is almost ready to be tested, needs a bit tweaking and testing.
Here is the progress.
Appreciate inputs from
I decided to build two version of the pre amp.'
First simple version build around PIC16F876A and PGA2310, having four input selector relays through ULN2803, an output buffer around OPA2314/OPA2107 or LM4562, a 20x2 LCD five butttons for up, down, mute, signal switching and power buttons and an IR based controller. One PCB of about 5.2x4.5 inches and an output relay to prevent power off thump
Second version is a high end one build around PIC16F877A, PGA2310, four input signal switching through ULN2803, input and output buffers on PGA, input buffers around OPA2134/OPA2107/LM4562 and output buffers around OPA627, five buttons like simple version, I.R, Rotary encoder, 20x4 VFD, and extension capability to six channel (another two) PGA2310 or a bass-treble control around AD5204/6. Three PCBs one for controller, one for analog section and one for the VFD and buttons, also an output mute relay to prevent power of thump.
As PCB fabricating has never been easier for me so I got two boards each.
What is left is an eternal wait for ICD2 to arrive from USA, to burn the mcu, software is almost ready to be tested, needs a bit tweaking and testing.
Here is the progress.
Appreciate inputs from
Attachments
Loaded simple pre amp.
My objective with simple version of the pre is to help those hobbyists who find it difficult to do such a project independently.
Once I see enough interest in the project I ll upload the hex file for non commercial, hobby use without any catch or I may even offer pre-programmed MCUs
For the high end pre I ll post development and populated PCBs, but I think right now it will be difficult to post the firmware as it requires a long time of research and head-scratching. Though I would offer PCBs and pre programmed mcu and a few other parts, but I ll revisit it to decide.
My objective with simple version of the pre is to help those hobbyists who find it difficult to do such a project independently.
Once I see enough interest in the project I ll upload the hex file for non commercial, hobby use without any catch or I may even offer pre-programmed MCUs
For the high end pre I ll post development and populated PCBs, but I think right now it will be difficult to post the firmware as it requires a long time of research and head-scratching. Though I would offer PCBs and pre programmed mcu and a few other parts, but I ll revisit it to decide.
Attachments
now comes the high end version of the pre-amp.
This is the controller board, some sticky material could be seen on jumpers.
Controller board has two IDC connectors one for the VFD, IR and Buttons Board and other for analog board. two connectors crimp shell one for the buttoned rotary encoder and one for ICSP.
Well I experimneted of putting silicone sealant on top of them to ensure that they dont move and dont get shorted.
Right now I will use the mcu in 4MHZ mode but I tend to increase it to 20MHZ once proto soft works perfectly.
This is the controller board, some sticky material could be seen on jumpers.
Controller board has two IDC connectors one for the VFD, IR and Buttons Board and other for analog board. two connectors crimp shell one for the buttoned rotary encoder and one for ICSP.
Well I experimneted of putting silicone sealant on top of them to ensure that they dont move and dont get shorted.
Right now I will use the mcu in 4MHZ mode but I tend to increase it to 20MHZ once proto soft works perfectly.
Attachments
Analog Board of the high end pre, one thing that I forgot to mention was that the both pre have two ground planes digital ground and analog ground, both planes tied together via single wire jumper and enough capacitors to prevent unwanted coupling issues, all resistors are metal film 1% type.
Attachments
Hi abid,
That's what I call a nice project
Why didn't you ordered ICD2 from olimex? it's fast😉
And what about the firmware?
You are writing it in ASM, C, other language?
Wanna share it?
Apart of comments about the design, you can get help with the source code.
All the best!
audioDIYer
That's what I call a nice project
Why didn't you ordered ICD2 from olimex? it's fast😉
And what about the firmware?
You are writing it in ASM, C, other language?
Wanna share it?
Apart of comments about the design, you can get help with the source code.
All the best!
audioDIYer
Looks great!!! I recently have been proto-typing a quite similar project (actually a mixer) using the pic16f877 and the SSM2160 6 channel VCA. ive recently dropped that project due to the fact that i will need quite a few ssm2160's. so that being the case..... do you like the PGA's? have you tried the VCA's from "THAT CORP"? just wondering how its all working for you. also what compiler are you using Microchip? MikroC?... if i get my project going again maybe i could consult with some of your deisgn ideas.
Great project
Great project
Guys Thanks for the nice comments.
Since I have limited number of grey cells in my skull 😀 😀 , therefore assembly is way over, for C right now I cant spare time to learn it, therefore I use PICBasic Pro for programming. I am already doing VERILOG,CFP alongside Job so time is a big constraint.
I have comitted to post the firmware of the simple pre here on the board, right now I am stuck in two problems first defining a good routine for signal switching, and how to put in the I.R codes.
Well For ICD2 I did buy one from microchip direct, unfortunately it fried due to voltage fluctuation, then I bought one off ebay its an ICD2 clone.
We have an anomaly in customs system here if I get any product via DHL, FEDEX,UPS, etc I have to pay customs from 100% of the value to 250%, however, if I get the same product via snail mail there is no customs. So this time I ordered via snail mail.
For firmware I am always open to suggestions/improvements and would really welcome any inputs.
Even for Layouts if there is any improvement required or something needs to be changed I could well do it.
Drummer_Dave:
I have used ssm2160 just once a few of them are still lying around. PGA seems a better choice for me when I compare it with SSM.
Though Dallas Semi make some good pots but then again I would prefer using PGAs. VCA from T.I are not suitable coz most of them are available in TQFP which I fine extremely difficult to handle.
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