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SIDprotector   [2016]

SIDprotector Released by :
Singular [web]

Release Date :
28 August 2016

Type :
C64 Hardware

AKA :
SID-protector

Website :
http://hermit.sidrip.com

User rating:**********  10/10 (5 votes)   See votestatistics

Credits :
Graphics .... Hermit of Samar Productions, SIDRIP Alliance, Singular
Design .... Hermit of Samar Productions, SIDRIP Alliance, Singular
Idea .... Vincenzo of Molecoola, SIDRIP Alliance, Singular
Test .... Vincenzo of Molecoola, SIDRIP Alliance, Singular

Download :
http://csdb.dk/getinternalfile.php/151463/DC-biased-audio-output-protection.png (downloads: 235)

Look for downloads on external sites:
 Pokefinder.org


User Comment
Submitted by Jak T Rip on 25 September 2016
Yes, prevent SID deaths please!
User Comment
Submitted by Hermit on 28 August 2016
I have to correct a little bit what I wrote about 6581 below: Actually it was not tested with direct 6581 output but through a replica of the transistor-stage of the original C64, including the 1kOhm resistor on the input which is required for the old 6581 SID-model.
So to be compatible with both SID-models I think it's best to connect the input of this circuit directly on the output of the transistor (emitter of 2SC1815 or 2SC945) in the C64 sound output stage (before the output decoupler capacitor).
User Comment
Submitted by Hermit on 28 August 2016
I designed this simple SID-protector some months ago as Vincenzo needed some protection for SIDs to record safely. I tested the circuit in ngspice (SPICE circuit simulator linux implementation), and Vincenzo built and tested it on real hardware. He didn't try to stress-test it for obvious reasons (too many SIDs died already in C64 history), but the circuit simulation shows that this simple circuit protects SID's output from overvoltages and reverse voltages/currents. If the diodes are of Schottky type (with enough reverse breakdown voltage for the task), the circuit can have less impact on the output signal due to the series diode and more protection in the negative voltage region on SID-output. 50V and more breakdown voltage diodes are preferred because in practice phantom power around 48V is the biggest that a mixer or other devices can drive to the C64 output by accident.
If the diodes are normal-type (e.g. 1N4148), then D2 in parallel with the Zener doesn't do much and can be left off...
The circuit only worsk with DC output of the SID (or maybe the transistor current amplifier output) and provides DC output which should be filtered with a series capacitor to remove the DC component of the signal or connected to the transistor current amplifier in the C64. The latter hasn't been tested yet, Vincenzo simply used RCA sockets to directly drive the outputs out from the C64... That worked with both 8580 and 6581 SIDs despite the 6581 having incomplete (non-complementer) output...

We hope this can prevent some further SID-deaths for people who try it...

(hermit)
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CSDb (Commodore 64 Scene Database) is a website which goal is to gather as much information and material about the scene around the commodore 64 computer - the worlds most popular home computer throughout time. Here you can find almost anything which was ever made for the commodore 64, and more is being added every day. As this website is scene related, you can mostly find demos, music and graphics made by the people who made the scene (the sceners), but you can also find a lot of the old classic games here. Try out the search box in the top right corner, or check out the CSDb main page for the latest additions.
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