How to protect sound card during amp measurements?
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 26th August 2008, 04:57 AM #11 okapi   diyAudio Member     Join Date: Aug 2004 Location: Buffalo ACD it would be easy enough to stick a 100K in place of the 909 and the 1K resistors and loose the 100 ohm. would this solve the problem? can you define VAS for me? thanks.
 26th August 2008, 07:55 AM #12 Jan Dupont   diyAudio Member     Join Date: Apr 2003 Location: Copenhagen, Denmark okapi; Changing the resistors to 100k and 1k would solve that problem. The VAS stage is the input Voltage Amplifier Stage (the circuit that amplifies the Voltage and drives the output devices) __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Spare time company (just for fun): www.dupont-audio.com
 27th August 2008, 05:58 PM #13 okapi   diyAudio Member     Join Date: Aug 2004 Location: Buffalo below i am summarizing my understanding of resistor value selection for the sound card protection circuit. please correct me if i am wrong as my electronics "knowledge" is self taught. choosing appropriate resistor values depends on what is driving the sound card protector as well as what the sound card protector is driving. in my case i am using a power amplifier and my computer sound card. in order to advantage of the full range of the sound card input i want the final voltage to be about 2 V. since i would like to test my amp at maximum output - 40V - i need to attenuate the signal by a factor of 20. i can do this with 1900 to 100 resistors, 19000 1000, 190000 10 000 etc. as i increase resistor values i am making the sound card protector easier to drive, however, i am also making it more difficult to drive the downstream sound card which i am guessing has an input impedance of about 10K. based on this i chose the 1900, 100 ohm resistance values (10 X less than the sound card) with 900/100 thrown in to keep my options open. if i went higher the input impedance of the sound card protector begins to approach that of the sound card which i think is about 10K. when i suggested using a 100k series resistor and eliminating the 100 ohm resistor i was going back to what was originally suggested earlier in the thread where i think it was proposed to use the sound card load as the shunt resistor. thanks again for your help
 2nd September 2008, 03:06 PM #14 Dan2   diyAudio Member   Join Date: Sep 2005 I have a similar project on my "to-do list" i have an occilloscope program on my computer that uses the sound card input, and also want to make a protection circuit for it. i want to make something that can cover a wide range of voltages without drawing too much current. so is this circuit the way to go???? as an added precaution, i was thinking of putting another sound card in my computer and using that. if i were to blow that sound card will it stil be able to blow the motherboard?? i will be using a desktop PC. i was thinking of using opamps for buffers, but they wouldn't offer any kind of protection, would they?

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         Dx Classic Amplifiers         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post Marik Solid State 2 2nd January 2012 08:59 PM kaluchka Chip Amps 6 20th June 2011 03:48 PM MMeche Digital Source 1 28th June 2008 11:17 PM TWOJZ Digital Source 0 3rd January 2008 07:01 PM argonrepublic Digital Source 0 11th July 2005 03:39 AM

 New To Site? Need Help?

All times are GMT. The time now is 03:53 PM.