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  1. hi again audioguru!! I have already sighted the article section. Thanks! it is definitely a big help,.. hahaha, Im going back to school again.. I have not been reading nor been in the environment for a year and a half that's why I almost forgot my lessons back from my school years.. I may ask you again some expert's advices in the near future.. hehehe.. anyway, thanks again!!! ---xoy---
  2. Hi audioguru!! I am really interasted to pursue a career in designing end developing circuits. As an ECE graduate, I have basic knowledges regarding electronics and the components. My problem that I want consult you is my problem in designing and developing circuits, like for example, timers, counters, amplifiers, using an LCD, and much much more... I know electronics is some kind of big big world, but I know I can be in my ambition to be like you as an electronics guru in the near future. Audioguru, can you please advice me on how I can effectively design and develop a circuit of my own. I will attach here a circuit, specifically "Electronics scoring game", can you please help me to know how to come up with this design. What I mean is knowing why they place a certain resistor in its poisition, capacitors, ICs and switches, thinking that there is no existing circuit like this and you will going to design a circuit of thison your own. How did they put or come up with the values of its component? what are the computations? what are the best steps to come up with the design of your own? I hope you will share me your greatness. Thank you. God bless. --XOY
  4. But you have only part of a filter since its R5 is missing. It will oscillate like that. reply: A.... sorry.. i now put the R5... If their values aren't the same then the filter will be messed-up with a droopy response or a peak and oscillation. If their values are less than 1k then opamps can't drive them. reply: i just change the R5 and R6, and just increases it as what you have advised me (at forum#13, reply #170 at electronic stethoscope forum).. A Schmitt-trigger doesn't do anything with its input connected to ground. Its input needs a rectified and filtered signal. reply: i have now tried to add the fullwave rectifier, not just pretty sure about the connection and the value of its resistor... The voltage across an LED is too low to feed a Schmitt-trigger. The voltage from the opamp that drives the LEDs is too high for a Schmitt trigger. The output from the opamp and at one of the LEDs has a negative voltage that will damage a Schmitt-trigger. reply: i have added the rectifier,.. i have thought that the shcmitt trigger inverter is use to invert the negative pulse to positive pulse... because the counter needs an input of positive voltage.. so what can you prefer to me the possibe solution.. i still have the circuit here... thanks again audio guru!!!!!!! _______xoy___________________
  5. hi audioguru, :odoes it mean, i can supply the electronic stethoscope2 with a positive and negative 6volts supply? whewwwwwww!!!!! so there is no need for me to have a converter??? maybe it is better for me to use 6vacdc adapter... i will only add what Alun advice me to have a -6v supply.. (at the #18 at the electronic stethoscope forum reply#245) thanks again audioguru!!!! -----XOY-----
  6. thanks audioguru... now i can have a better discussion with you now... answer at #1: you adviced me before to have a 2nd Ub1 stage, so i put it after the first Ub1 and before optional stage... answer at #2: i use trimmers intead of resistors so i can easily adjust the frequency.. answer at #3: it is already connected to the ground of the optional stage.. i have tried to connect the input of the schmitt trigger to one of the LED so that only the thomping will be counted and not the thumping... (thomp-thump) answer at #4: i have seen so many rectifier circuit.. what is the best fit to use? is it the half-cycle rectifier circuit?? (http://www.allaboutcircuits.com/vol_3/chpt_3/4.html).. is it connected after the optional stage or before?? answer #5: i now connect the Q3b pin of the CD4518 of the timer at the hold pin of the counter so that after the timer reaches the corresponding time, the counter will hold the counting... i add a diode so that there is no return voltage.. >>the phase lock loop circuit or IC is still not included, maybe i should finish here first, before i get to the PLL... thank you audioguru for patience... thanks!!!! ------XOY-------
  7. hi again!!! i ask my teacher for that beeps, but he is really forcing me to have an output in an LED display.. i have simply just design two circuits here, but this really needs any corrections... can you please help to get through this... thanks!!! i get the circuit of the counter and the timer on (http://www.electronics-lab.com/projects/oscillators_timers/014/index.html) and (http://www.electronics-lab.com/projects/oscillators_timers/015/).. i also add another Ub1 stage to pass the heart beats sounds only... tnx in advance.... merry christmas!!!!!! ------xoy----
  8. hi!! what kind of microprocessor is used in the Omron automatic blood pressure monitor???
  9. hi!! what kind of diode?? is it s silicon diode?
  10. hi audiouru!!! i will going to use that on a digital sphygmomanometer which has a 6v input... it will be acompanied with another circuit which has a 9v input... is there still any way for this?? --thanks!!! ----xoy---
  11. it is marked 473.. so it means it is ok to use... thanks!!!
  12. hi audioguru!!! i know, i should have learn more.. maybe thats a better idea.. how can i properly make it beep!?? which only beeps on heart beats... thanks!!!
  13. hi!!!! can anyone help me please how can i convert a 9v from battery to 6 volts supply.... please post a circuit.. thanks.....
  14. hi!!! i cant find the 0.047uF/50V Metalized plastic-film Capacitor, instead i buy the mylar capacitor with that same values... is it okay???
  15. hi audioguru, alun, and other eletcronic gods there.... i know this is another topic to be discussed in the part of electronic stethoscope so why i build this new page... due to financial problem, i was seldom replied in some of of my discussion about some of my questions.. in the other page of electronic stethoscope.. so i just wanted to focus here,, here is the situation, i just wanted to have sure answers.. althuough audioguru have help me a lot, i cant still understand because of i have lack of knowledge about this.. i was preparing for my project to build a amplified digital stethoscope.. due to lack of knowledge, i am very please that you can show me a circuit or schematic diagrams... please help... i will be very very glad if you still continue helping me regarding this.. thanks.... 1. i just want to have the electronic stethoscope, to have an output on at least a 1kilowatt amplifier and speaker. So that we can hear the sounds on our class. 2. i just want to have this electronic stethoscope, which will display the heart rate (or heartbeat per 60 seconds). the dispay must be in 3 digits, because the heart rate may exceed over 100. (hi audioguru, i am very interested on what are you trying to tell me regarding the 6 seconds, i just cant hardly understand it, but im near now to undesrtand it...) this is what you suggested me before regarding this.. A 1 minute update on a stethoscope is a long time to wait and to see any change. You could use a 6 seconds timer for a quicker update, then add a zero to the display to show beats in 60 seconds. You could add a phase-locked-loop with a digital divider to multiply the frequency of the beats per minute, then display them accurately in beats per 0.6 seconds, updated every 0.6 seconds. i really like the idea, i just cant hardly understand it without any circuit.. but i know this is quite feasible.. Can you plaese post at least a circuit of this, regarding to my counter ciruit. 3. i just wanted to have this electronic stethoscope to have another back-up supply. A 9VDC AC adapter will be used as the other supply, with the two 9V batteries. When the 9VDC AC adapter is used, the connection of batteries will be automatically cut-off, so that it wont supply. ive got the answers of this at the page of electronic stethoscope. but what i dont know is when i use the 9VDC AC adapater, how could the connection be automatically connected to the 9VDC AC adapter, and automatically disconnect to the batteries. here i will post a circuit, please edit. Please take out what is not needed, just add if there is needed.. just coerrect it please... any help are vere highly appreciated.. plase help thanks...
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