kross 0 Report post Posted October 28, 2005 hmm...din know that op-amp rolling would cause so much trouble. din u use sockets? if so maybe u can change back to ur opa2137 and see if there is still oscillations. also, from my experience, when my 9v is going flat, oscillations start to occur but they disappear after i change to a new battery, which is the battery pack i am currently using. from what i know, 2228 is used when the gain is 5 or higher iirc, so maybe your cmoy2 gain of 2 is too low for 2228? Share this post Link to post Share on other sites
kross 0 Report post Posted October 28, 2005 I see at home make your own power supply even more economical I'll make one myself maybe when I'm going to start I'll check with you again. the resistor values.. hmm... I've got made some changes the input line high pass filter, I've increased them to 100k each. make the attenuation freq 10 times lower. it means that more bass freq can pass thru instead of going off to drain hehe ya, i am thinking of making a home power supply using one of those 9v adapters which i have at home but tat has to wait till my exams are over. i'll check with you again too. hmmm...what extra frequencies are you passing through. dunno whether our ears can listen to those frequencies since the lowest audible frequency is about 20Hz. Share this post Link to post Share on other sites
Kube 0 Report post Posted October 28, 2005 Hmmm, thanks koss, at least now I know it's not that it's fried or something. Ok, will stick to opa2132. Checked with a multimeter, voltage of the 9v is still quite high, around 7 - 8, so I don't think it's the battery. Is there a possibility that I might have burned the pot? Perhaps I heated the pad or the legs for too long. Also, might a dirty IC socket have any impact? In which case, how could I clean it? Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted October 28, 2005 You just have to take care not to drive too much current as it will distort like hell. May I know the source of distortion? the MAX4167 as far as I've read its data specs, it cant drive high voltage neither high current then with no LM6171, wat's the direct impact? the virtual ground not as precise? am I correct? as there's a lack of buffer hence the v ground will be affected by load itself? luckily, I have no high impedance cans highest I have is 60 ohm only The LM6171 has a low impedence output. Taking it away and driving loud would sound...... funny. Not precise is another thing and yes, it will be affect by the load. Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted October 28, 2005 You just have to take care not to drive too much current as it will distort like hell. hmmm...i am using a battery holder pack with 8x 1.5V AA batteries inside to make up about 12V for my cmoy2. like this should be ok right? how to not drive too much current? if voltage is around 12V current should be ok for the amps to take it right? Only when you drive it loud enuff than you will hear it. Now your Cmoy2 has downgraded to just Cmoy... Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted October 28, 2005 (edited) Hmmm, thanks koss, at least now I know it's not that it's fried or something. Ok, will stick to opa2132. Checked with a multimeter, voltage of the 9v is still quite high, around 7 - 8, so I don't think it's the battery. Is there a possibility that I might have burned the pot? Perhaps I heated the pad or the legs for too long. Also, might a dirty IC socket have any impact? In which case, how could I clean it? SHOW ME THE PEEKTURE!!! Ahem.. Your 7-8V issit alkaline? Edited October 28, 2005 by jasonhanjk Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted October 28, 2005 Lol. I'm also apprehensive about the meet. Don't want to be the only young guy there, as it seems alot of members here are old and working...Thanks anyway. Thanks jasonhanjk, hope to see you this sun. Btw, do you do drilling too? Don't have a drill at home, and I don't want to screw it up then go all the way down to eunos just to get another casing. Need to follow an experienced diyer. find me I can help u "provide" drilling tools other machinery... err.. a bit complicated. but can be worked out with btw, drilling is such simple job if you've got all the right tooling Meet sunday where??? Share this post Link to post Share on other sites
Kube 0 Report post Posted October 28, 2005 Yeah, it's alkaline, or at least I think it should be. Why? Need to go borrow a good camera to take. Erm...nevermind about the drilling, take it one step at a time and just get the darn thing to work. Share this post Link to post Share on other sites
kross 0 Report post Posted October 28, 2005 ermm..jason in ur above post, u mean taking out the lm6171 'downgrades' the cmoy2 and not using 8x 1.5v battery pack 'downgrades' the cmoy2 right? Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted October 29, 2005 Yeah, it's alkaline, or at least I think it should be. Why? Need to go borrow a good camera to take. Erm...nevermind about the drilling, take it one step at a time and just get the darn thing to work. Had you tried a fresh new batt? 6-7V for 9V alkaline is as good as dead. Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted October 29, 2005 ermm..jason in ur above post, u mean taking out the lm6171 'downgrades' the cmoy2 and not using 8x 1.5v battery pack 'downgrades' the cmoy2 right? Not using LM6171 downgrades it. If you can find another single opamp IC that have low voltage spec to replace it, that will be better... Once you use low voltage opamp, it should be ok. Share this post Link to post Share on other sites
Kube 0 Report post Posted October 29, 2005 Wow, 6 -7v, and it's dead? Hmm...that what kind of batteries does one use? Nimh rechargables require a full discharge before going to charge, right? Share this post Link to post Share on other sites
squalle 0 Report post Posted October 29, 2005 for the input cap, look here: http://www.tangentsoft.net/audio/input-cap.html even tho the attenuated freq is way too low for us to hear, I think the graph in that link, or the graph being linked up from that site can show very well why the need of the attenuation way lower than what one can hear. and yeah, I agree with jason, taking out the v ground op amp somehow degrade it in the sense of the output impedance will suffer (higher than with LM6171). however, now I've got a replacement op-amp that can run at similar voltage. well, I guess I was stupid. haha. actually the MAX4167 has within its family another similar one, MAX4166, single op-amp, DIP form factor. so yeah, currently I'm waiting for it. abt the NiMh batteries; one dont need to discharge it fully to recharge. here's the comprehensive answer to that: http://www.batteryuniversity.com/ in gist, actually it's not advisable to purposely discharge it. no such thing as memory effect on NiMh batteries. maybe true for NiCd. but who use NiCads nowadays? hehe Kube: regarding the 9v battery, yeah it sux. that's why I try my best to avoid the 9v batt. but u've got the 8 AA batts. so make use of them. a lot better. able to withstand a hell lot more current draw than the 9v batteries. anyway, are we supposed to meet up? need details on where n when please. hehe Share this post Link to post Share on other sites
Kube 0 Report post Posted October 29, 2005 Eh? I was of the opinion that all alkaline rechargables need to be fully discharged, and that the only batteries without memory effect is that of Li-ion batts...Ah well, rusty memory Can you troubleshoot the board? Hmm...my poly's just starting, so I won't be as free. Hmmm...PM me when's conveniant for you to help, and I'll see if I'm free too. Thanks, anyways Share this post Link to post Share on other sites
squalle 0 Report post Posted October 29, 2005 hmm got alkaline rechargables? come to think of it, yea there were once. but I guess they're not popular. can help u. but yeah, when can we meet up? haha without meeting up, how to troubleshoot? hahaha which days are ur free days? weekends? Share this post Link to post Share on other sites
