hakyman

hi everybody , me and my friend have designed( actually changed smth on a schematic:) a reg for non simetric transformer the point is the transformer connections. its workin ok now, but i dont have a chance to measure or see all effects on output, is that kind of connections has a disadvantage , we dont have a simetric output transformer right now so we have done that, pls help us for a further and better reg with output of + and - voltage. and if u got any other opionions pls let us now, for eg. current amplificaiton . we thinkin about add some outputs for stabile +5v +9 +12 and we have to take theese outputs from the connection point of c3 and c5 too, unfortunately this transformer is the only big power transformer we have got, it has 0 24 48 volt ac outputs, i can find a lineer one like 48 0 48 around also they are a little expensve for us so we use it like this is that effect bad?or what could happen? any modification idea or needage for better reg? thnx for help sorry for bad english :)

Hi Hotwaterwizard thanks for the reply i have the datasheet but i'm searching for a replacement cause it cant be found at electronics shops at around. thanks best regards

Hi i need to learn if there is a replacement or similar part to CA3237(IR preamp). cause i cant find it around thanx best regards

hi Audioguru i did not do special cahnges on filter block still sallen n key type but i just set the cut-of to 1500Hz coz i said before i work on both heart and respitory sounds and respitory sounds range is 70-1200 hz. i added a digital filter at 8th degree to choose the heart sounds. i know the analog filter seems useles but teachers said there should be an analog type filter so i added:) very very best regards

hi Audioguru Here is my measurements(all values r max, means i hit the stethoscope head as strong as i could do ;D ) output of steth. circuit; ACV =1.5V (with no load) DCV =+/-1.5V(with no load) ACA =12mA (with no load) resistance in ohm of PC sound car dmic input=unreadble(over 20Mohm) when the circuit connected to PC sound card mic input ,current flows to PC; ACA=0,950 mA additional info = sound card adds a 0.02mv Ac componenet onto real signal i use 9V alkaline batteries and i limt the circuit output voltage with limiter dioades and i set the volume as low as possible cause my main purpose is monitoring the heart and respitory sounds so i did some differences on filter block. i dont fright from the output voltage but i'm not sure about the current but 0.950mA cant damage any kind of sound card i guess :) but i want to be sure and what do u think. is there any value have no-sense or unexpected??? specially is 0.950mA too low for 1.5V in AC ? thanxxxxxx

hi Audioguru i'm not powering the mic from sound card. i use the sound card as a receiver for PC like the Rf TX circuits connected to the PC. actually its again about the ur electronic stethescope project. i wrote a parallel port and sound card program to monitorising the sound and added a digital filter for better responce but i got some problems with par.port while real time monitrizsing and matlab have so much advantages with sound card mic input. generally sound cards powering voltage is 5 Volt (for stereo)so i think it will accept the 5V but i'm not sure about the current. i tryied the circuit at different 5 PC and had no problem it acts well but i would like to learn standart if it exist :) i dont think the output of sstethescope project damage any sound card but i'm not sure again .. thanxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(and i will add ur name to my thesis "thanks to" part:)

hi everybody i'am searching for a standart for sound cards but i cant find smth about it. i read much tittles about it but there is no standart i could find. is there a standart for sound cards for Acceptable voltage to mic input?????? or what is the worst sound cards max aceepptable voltage for mic input. i working on it and i have no problem with my sound card(ac97 cmedia) with max +/-1.5 V DC but what about other sound cards ?????? thanx

hi guys thanx for the replies audioguru could pls make it some clear cause i dont see ever a mouse kit with rf i only use IR kits. and do u know a link have some schematics without a needage of antenna of transmitter. u can write to the link to alun gave at above where u discuss about transmitters . thanx very much very very best regards

hi Audioguru !!!!! how r u ?for a long time later i come back :) i finished the circuit and the matlab program to analyse the heart and respitory sounds.thank god :) anyway now i want to add a trnasmitter and receiver circuit because the cables really annoying hehe anyway what u suggest? i am searching for a simple, stable, and if possible without a needage of antenna hehe do i want so much things . i know i should write theese in another topic.but i want to get ur opinion . thanx very very speciaal regards ciaooooooooo

hey guys ; i have got a little problem here , i bought a phototransistor but i cant find the datasheet . the only thing writed on the device is ; 3E 1001 D , i ahve searched in net and datasheets but i cant find something. i think the numbers are explanation numbers its a 3 pin phototransistor. pls helps thanx already....

thanks for the advice

hey what is it i dont know what is afun card ? could anyone explain that what is used for ? thanx and sorry for ignorance:)

hi audioguru. how r u do you remember u recommended using a peak detector and a rectifer circuit to me to fix the output for an ADC. i tried so many times the peak detector circuits and i cant get the reason for using it. i use a adc0804. and the peak circuit just do the sampling duty like the ADC circuit can make it own. if i change the capacitor values of peak detector(change time duration) the circuit only help to find the max. peak of a cycle. and may i ask which point is the best for taking output to ADC.is the output point of amplifier(LM386) or output of the filter part. which one should i use. my amplifier(lm386) output is about 4.2V without a sound in the mic(change with the volume control pot.changes and it can up to 4.5V). and it swings with a heart sound around 4.2V(about 3.7-4.8) could i use the ADC directly and last one thing i use the 5.th pin of LM386 for output taking before 1000uF which its anot goes to headphones jack. this is all :) i am very dogged to get the knowledge. if u can send me a circuit or just a block diagram i'll be so much happy and thanksfull. i search so much but i cant understand the death points of the circuits that help me find the circuits how to work. may be my english is not sufficient or may be their english is worse than me :) whatever thanks already.

hi all what about low frequencies is there any solution without taking the antennas lenght bigger?or is there any type antennas has small dimensions?

Hey Audioguru You did again thank you so much for your kind and quick reply again i dont really know how can i thank to you thank you so much i'am gonna out of city for a week time. so i ll send the LF353(jfet) setehescope with a LM386 amplifier after i came back. see you thanks for all