*** BUILD A *QUALITY* AUDIO DIGITIZER FOR YOUR AMIGA FOR UNDER $20 !!!*** OK, I finally got my audio digitizer working after a lot of help from one of the applications engineers from National Semiconductor. He works on the team that came up with the A/D in this project. Thanks a million!!! On to the fun stuff!!!! First off, here is the correct parts list. DON'T use the other ones below from the original articles!!! They are WRONG!!!! ---------------------------------------------------------------------------- 1 ADC0804 A/D Convertor 1 LM386N Audio Amp 1 100K Trim Pot 1 .1uF Capacitor 1 10uF Electrolytic Capacitor 1 47pf Disk Capacitor 1 10K Resistor 1 DB25 Male connector 1 Female RCA or Mini jack ---------------------------------------------------------------------------- I built mine on a piece of perf board 2" x 3.5" in size. Drill holes for the RCA jack and the 100K pot shaft. Make all the solder connections as shown in the schematic I drew. I take no responsibility for any problems caused by or resulting from this schematic. I drew it exactly the way that I have mine wired up, and it worked fine! I suggest using sockets for the 2 IC's as the ADC0804 cost ~$12.00 !! Pick a good layout before doing the project because you can get this thing really small if you try hard. I made the mistake of laying mine out poorly, and ended up having to cross over the 8 data lines from the A/D to the DB25!! Think ahead and save yourself some trouble. I have used the digitizer with AGMSRecordSound/Playsound, MED 3.21, AniMan, and VCLI4. It has worked great with all of them. The quality of the samples it takes can be very good. One thing that I have noticed is that electric guitars and high pitched rapid sounds tend to sound very scratchy, but this is pretty common on digitizers. For $4.95, Radio Shack also sells a cheepo-microphone. If you are just in this to play around with VCLI and AniMan, then this is the perfect thing to get. Future Possibilities: In an attempt to alleviate some of the scratchiness, I might attempt some sort of filter subcircuit. According to my boss (an EE) this should take care of the problem, and reduce some clipping at high volume levels. Alright, here is the original documentation. Use it more as a guide as to what can be done with this project. DON'T USE THEIR PARTS LISTS!!!!!! If you have any problems, I can be reached at kopackm@lonex.rl.af.mil (summer time only!!!!) gt6758b@prism.gatech.edu (rest of the year!!!!) Good luck!!!! --Mike Kopack ************************ READ AT YOUR OWN RISK ************************** ORIGINAL DOCS NOTE: Although I re-typed these instructions off of paper, I take no credit for the contents of this file. I typed exactly what I read off the paper and only made cosmetic changes to the look of the text file. Meaning, I only made it look better. I did not, to the best of my knowledge, change any of the wording or directions that follow. I also re-drew the schematics off paper using Deluxe Paint. Use a IFF picture viewer to see this picture, contained in the file called Schematic. Again, I only made a few cosmetic changes to the look of the schematic. I can not be sure that I didn't change something along the way of typing or drawing it on the computer. For this reason I must say that I can take no responsibility for any damage that may come to your computer system from using this device. Use at your own risk! OK, now that that is out of the way, let me say this. I am very impressed with samples I've heard from this audio digitizer. It can be built for $15 to $20 dollars and consists of 9 parts! You can make a PC board for it or simply wire everything together. It will work with Perfect Sound, Audio Master II, and several other audio digitizing programs on the market. The sound quality is as good as any comercial devices I've heard samples from. It uses the same audio to digital conversion chip that the Perfect Sound digitizer uses. The only drawback to this device is that it can not sample in sterio. By this I mean that it can only sample one channel at a time, the left or right channel. This is not a problem, as a program like Perfect Sound will let you get around this. To create a sterio sample you need only to do a little more work. First sample the left channel, then the right channel, and then choose the menu command to create sterio. The software will then splice the two together to create sterio! I'd say this is a minor price to pay for saving $80 on the price of a sterio digitizer. I was told to try Jamaco Electronics at 1-415-592-8097 for the rest of these parts, but I'm sure a lot of other places also carry them. There are a lot of different types of plugs you can use in place of the RCA type. Simply choose the type you want and if it will be male or female. Most people will use a female RCA plug. Get one that rack-mounts. I also picked up a small plastic box with IC project-board, 8 screws, 4 rubber feet, 2 label panels, all included in one package (Part 270-291a). It measures 3 7/16"x2 5/16"x1 3/16" and cost me $4.49. There are several small PC boards and cases at Radio Shack that will work fine. Just remember to think small. This layout doesn't need much room. I plan to melt (I always use a screwdriver to melt my holes instead of drill them.) two holes into this case. One will be in the middle-rear side of the box for the RCA plug. The next will be on top of the box for the pot. I also plan to cut a hole, using a hot exact'o knife, into the front of the box for the printer port connector. One hole will be melted on each side of this for two screws to hold the printer connector in place. A few labels, here and there, and we're all done. There are many ways one could go about building a case for this. I just thought I'd give some people an idea. Before you digitize something your going to want to set your input level. If the input level is too high or low, the recording results will not be as good as they should be. To do this via Perfect Sound: 1. Choose "View Signal Levels" under the "Digitize" menu option. 2. Look at the "L" (Left channel.) or "R" (Right channel.) display at the bottom of the screen. Three numbers will be shown. The first is the smallest value ever digitized, the next is the highest ever digitized, and the last number is the current value. If your input level is too high ,then the smallest value will stay at 0 and highest value will be around 255. If your input level is at too low a level, the values will change only a little. 3. Adjust the volume of your output device and the pot on the digitizer until you get the right readings. Now your ready to digitize. Changing the sample rate will alter the quality of the recording. A high sample rate will give a good recording, but eats up memory a lot faster than a lower sample rate. Certain samples will sound fine at a low rate of 8000, or less. While other samples will require a sample rate of 10000, or more. Play around until you find the best setting for what your doing. Hope I've helped made the project a little easier for some of you. What follows is the original instructions. You can reach me on CA-AUG at 216-292-4404. Bob Cramer -------------------------------------------------------------------------------- This is a simple two chip audio digitizer for the Amiga (Specifically the 500, but the DB25 pinouts can be changed for the other models.). The parts list is: Qty Item/Desc Value ----------------------------------- 1 Resistor 1K 1 Pot 100K 3 Capacitors .1uF,47pF,10uF 1 Mini Plug or RCA Plug 1 Connector DB25 1 A/D Converter ADC0804 (HeathKit usually has these.) 1 Audio Amp LM386N (Radio Shack) This circuit will work with the program from the Perfect Sound digitizer with one small exception- it won't digitize in stereo. All the Vcc's (Pin 20 on the ADC0804 and pin 6 on the LM386N) can be powered from the printer port (at least it is working for mine with no power supply problems!). Use the monitor signal level option in the Perfect Sound program to adjust the pot to the correct level (NOTE: If the circuit is hooked to a line level- e.g. to the Audio-Out of a VCR or sterio- the pot should be turned WAY down. Just listen to the "monitor" and you'll see what I mean.). I do have this circuit built and running on my Amiga so I know it works. I just hope you can read the diagram! Jamie C.MUELLER (GEnie) -------------------------------------------------------------------------------- The digitizer plans were made to connect to an A500 parallel port. However, this will not work on the A1000 without some changes. If you have an A1000: Pin 10 (ACK*) is the same on both the A500 and A1000. Pin 2 to 9 (Data bits) don't change either. Pin 14 in the A500 is +5V (100 mA). Use pin 23 on the A1000 for this. Pins 17 to 25 on the A500 are signal to ground. Use pin 14 on the A1000 for this.