OhYeah 0 Report post Posted February 9, 2004 Using OPA134PA. First attemp with electronics. However after going thru some of the posting in this forum and headwize, managed to get it working. Love it with my Sen HD580 . No pics as it all in a mess ;p, just wanted to have a experiment. I will be attempting with a 2nd one with with 2x9v PS, 0.22uf cap, buf634 for output and virtual ground. Last but not least a casing ;p. And maybe a try with OPA637BP (will appreciate any advise when using this opamp) Just need to find a better quality pot for volume control and DIP-8 IC sockets. Thanx to all again! Share this post Link to post Share on other sites
huangyong 0 Report post Posted February 11, 2004 i think the gain for opa637 must be greater than 5... if i m not wrong.. Share this post Link to post Share on other sites
tropicalrips 0 Report post Posted February 11, 2004 the opa637 is single channel right? is it also surface-mount? Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted February 11, 2004 5 and above. Single channel DIL. Share this post Link to post Share on other sites
OhYeah 0 Report post Posted February 13, 2004 i think the gain for opa637 must be greater than 5... if i m not wrong.. CMoy configurations is using a gain of 11, so i think shouldnt be a problem. Anything else i should note? Share this post Link to post Share on other sites
OhYeah 0 Report post Posted February 13, 2004 the opa637 is single channel right? is it also surface-mount? yapz single channel. Dip8 Share this post Link to post Share on other sites
OhYeah 0 Report post Posted February 13, 2004 This is my experimental unit Mk1 ;p with OPA637BP. Thoes who love strings instruments should try it out. The plucking of strings is more define than the OPA134PA IMHO. This is my current project. However, the output is low and kind of distorted. Can anyone point out to me where is wrong?? Share this post Link to post Share on other sites
jtfoo 0 Report post Posted February 13, 2004 (edited) A suggestion, see if it helps to include a inner feedback loop of greater than a gain 5 for the OPA637. This would make it stable. Attached is a picture which I copied from the Meta42 schematic on how to implement.. Edited February 13, 2004 by jtfoo Share this post Link to post Share on other sites
OhYeah 0 Report post Posted February 13, 2004 ic ic will try! thanx! Share this post Link to post Share on other sites
OhYeah 0 Report post Posted February 13, 2004 (edited) now have to figure wat the circuit again ;p Edited February 13, 2004 by OhYeah Share this post Link to post Share on other sites
jtfoo 0 Report post Posted February 13, 2004 Why not use OPA627 or others that is unity gain stable? No need to change your circuit. Share this post Link to post Share on other sites
OhYeah 0 Report post Posted February 13, 2004 still waiting for OPA627 to come. Got my 637 first so use it first. Share this post Link to post Share on other sites
OhYeah 0 Report post Posted February 13, 2004 To all, went thru my circuit again just now. Just realise i solder a wrong resistor ;p. Swap them and Mk2 is now working well Share this post Link to post Share on other sites
