Music System from Processor Technology

General discussions related to the Altair 8800 Clone

Music System from Processor Technology

Postby Drunkle » May 27th, 2015, 2:02 pm

I do not know how many of you have seen the "Music System from Processor Technology" video and web page (http://altairclone.com/music_system.htm) here at the Altair Clone web site. I do not know if Mike plans to build something already for this. If he dose, I'll just wait for his.

I created a Clone version PC board to install in my system. See attached. The plan is to make an aluminum infill panel for one of the unused serial holes on the back of the clone and then using the 3.5mm audio output connector on the PC board to attaching it to this panel. This would give audio access on the back of the clone.

As an optional idea, maybe add a 1 watt audio amp circuit to the board so only a basic speaker would need to finish the project. This version can be mounted inside the clone. While this additional amp circuit would detract from the simplicity of the original design, the overall result may be more useful in the long run. In either case I would only produce one of the two designs. Simple or amp.

If I do move forward on this project, is anyone interested to have a board or two. I'm not looking to make any money from this at all. I'm going to cover the setup charges myself. This would be only a one time order of boards. I only wish to cover any additional costs to order extra boards and have them shipped.

What is your thoughts?
Attachments
Altair Clone Cuter Audio Interface-V1.jpg
Altair Clone Cuter Audio Board-V1.jpg
Not to scale
Last edited by Drunkle on May 28th, 2015, 9:33 pm, edited 1 time in total.
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Re: Music System from Processor Technology

Postby toml_12953 » May 28th, 2015, 6:52 am

If Mike doesn't produce one, I'd buy yours. A built-in amp would be best for me.

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Re: Music System from Processor Technology

Postby AltairClone » May 28th, 2015, 10:26 am

Cool idea! I'll sit back and let you have the fun on this one :)

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Re: Music System from Processor Technology

Postby toml_12953 » May 28th, 2015, 11:18 am

OK, it looks like Mike isn't going to make one. In that case, I'm in!

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Re: Music System from Processor Technology

Postby Drunkle » May 28th, 2015, 9:32 pm

So here is the schematic for V2 of the Altair Clone Cuter sound board project. This version now has a <1 watt amp using the old dependable and easy to find LM386N. The design has both a volume and a power switch as well as both an internal and external speaker plugs.

My vision right now is to mount the amp board using both the power switch and the external speaker 3.5mm plug to a serial infill panel. This infill panel will then be bolted to one of the serial holes on the back of the clone. I get the power to drive the board by unplugging the clone's fan from J5 on the main board and placing a three pin though cable between boards. The fan is then plugged in to a three pin connector on the amp board which just passes though power to drive it. This allows you to turn the amp off along with the clone using the front panel power switch. The extra three pin plug is for another project I have done that also uses the clone's front panel power switch.

I need to find out the current rating of the clone's power switch to see if it will be the switch or the clone's power supply that is the limit for current. The amp by its self at full volume draws less than 300mA at 12V in to 8 ohms. So there should be no issues with just the amp. My test unit is plenty load using a 70mm speaker! I had to all my family members come to my lab to see what I was doing.

All part used are easy to find at Digi-key, Jameco, etc. If we still had Radio Shack, I think most of the part where available there.

So the basic design is shown. I'm going to think a little more about how to optimize over the coming days. What are your thoughts?
Attachments
Altair Clone Cuter Audio Interface-V2.jpg
Testing Prototype
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Re: Music System from Processor Technology

Postby Synoptic » June 1st, 2015, 10:18 am

Ah ! this is great !
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Re: Music System from Processor Technology

Postby gio74 » June 3rd, 2015, 1:00 pm

count me in I want one!
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Re: Music System from Processor Technology

Postby Drunkle » June 3rd, 2015, 10:16 pm

Well here is the component layout of the finished PCB artwork. It follows the above schematic. The board layout uses the power switch and external speaker connector on the board to hold the board assembly to a metal plate sized to cover a serial hole on the clone from the inside. That assembly gets mounted to the clone's unused serial holes using the two mounting holes on each side of the serial connector hole. This given access to the power switch and external speaker plug on the back of the clone without having to drill new holes in the case. In addition the board is sized to place the two holes on the end with the switch and external speaker (the right side) in alignment with the two mounting holes them self. This gives the option to use two small 90 degree mounting brackets to also help support the board. I do not think this will be needed but it was simple enough to include just in case.

I tried to place volume knob within the same serial hole as the switch and connector. There just is not enough room there so I placed the volume on the PCB. In the long run, once you have the volume setup you may not wish to adjust it again. If you would like to have access from the back of the clone, the serial hole to the side (right or left) of the PCB assembly can be used to panel mount a volume knob. Then a short three wires run can be soldered between the PCB and the volume knob.

The next step is to order parts to verify sizing. Things always work well on paper but never really work fully when a unit is built. There are two parts (switch and external speaker connector) I do not have in my lab stock. I want to see them, fit them, prove them in person and not just via the on-line data sheets.

If all measures up correctly, I will then order a batch of boards. Given the low quantities, I'm going with two sided boards with plated holes but without silk screen or solder mask. ~$6 vs ~$21 per board.

Anyone have thoughts?
Attachments
Altair Clone Cuter Audio Interface-V2A.jpg
The marks of the rights side are clearance and centering marks for a clone's serial hole.
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Re: Music System from Processor Technology

Postby Synoptic » June 5th, 2015, 7:12 am

looks good !

I want one !
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Re: Music System from Processor Technology

Postby gio74 » June 6th, 2015, 1:46 am

I'll get the $21 board.
:D
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