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summersnow

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  1. Hi. I really don't know why..i read all of the application note and the spec for the chip and i still not able to find out the problem... Audioguru, i read the spec,it shows that 16 ohm is the minimum impedance..but it stated that 8 ohm is acceptable,just that will cause distortion and the sound is not tat big...so,is it that if i'm using 8ohm speaker,there should be some noise or sound? ??? i try to look for the data sheet for the electret microphone ..i try to fix the electret mic backwards but the result is still the same..no sound at all.. :'( From the application information for chipcorder products,it stated that there should be 1.5V at the speaker pins when PD pins is low and the playback/record is high... 0V if the other way round..my circuit meets the specs..but it cant play at all..n i wonder it is able to record.. Any other suggestion on this?Really don't know how to continue... :'( Really thanks if you all can help..
  2. Hi all, I have a problem here. I'm using ISD2548P as a speech IC to record the messages that i need to use for my project.I follow the PUSH BUTTON circuit that provided in the data sheet to record the messages.I try to record and play the speech but nothing can be heard when i play it. :-\ From the Winbond/ISD chip corder FAQ list that i found,it stated that when the device are in Record,the MIC,MIc REF, AGC and ANA OUT pins are all setting at approximately 2.2V,and when they are in Playback,the speaker pins are biased up to an average of about 2.2V.. When i measured those pins for my circuit,the voltage that i get is 1.5++V..so is it because of the voltage not high enough that makes the speaker can't play the speech? Is there any problems for this circuit? The input voltage for this circuit is 5V and i'm using a 8ohm speaker. Please help me on this..Thanks
  3. hi.. actually the D3 is to limits the voltage drop across the LED of the optoisolator to protect it from negative voltages,therefore avoid any possible damage..
  4. Hi audioguru.. Sorry for the fuzzy JPG file.. Thanks for your advice and i will try my best to learn more about the electronics to finish this project. i'm really a newbie for this.. Really thanks for helping so much
  5. hi audioguru.. thanks for reminding.. actually,i write wrongly in the circuit..i'm using 16V zener diode.. anyway,after i change the resistor to 10kohm,the ringing detector circuit works.. Thanks for your help
  6. Hi all.. I have a problem here. i tried to build a ringing detection circuit. But when i connect the ring and tip of the telephone cable to this circuit,i found out that it automatically being off hook. As a result,it cant be used to detect the ringing signal and it get engaged when i call to the telephone. Is there anyone who can explain to me why it get off hook even there are no ringing signal? Thanks in advance
  7. hi Thanks for your explanation :D I understand how the circuit works..but i don't know how to choose the component which can be used for this circuit,such as the resistance of the resistor,the diode and etc.. I havent buy any component or battery to build this circuit. Would you mind suggesting me the component which suits the circuit and can be obtained easily? i found two circuits which seems like have the same function as i mentioned before.. Would you mind to have a look and give the opinion on that? Do you think that it can be combined to meet the purpoes as the previous circuit? If the circuit can be used,can you please explain the transformer and the rectifier in the circuit? what kind of transformer and diode need to be bought for this? If you have no idea of both circuit,can you please design one for me? Really need your help..Thanks in advance
  8. Hi all.I found a circuit which basically works like this... A replaceable and rechargeable back-up battery and a ring-controlled switch circuit are provided to the rectifier of this invention to keep the machine working in case of an unexpected failure of the civil power or in response to detection of a phone call from a far distance to a ring-controlled switch for effecting a continuous power supply. Under normal conditions, the civil power is used to charge the back-up battery as a stand-by power source. what i want to do now is i would like to build up this battery backup circuit. however,i faced a problem here is there are no part number for this circuit and i have no idea how to figure out the part that in use.. what i mean is i don't know how to figure out the resistance,or the rectifier in use.. Is there anyone who have an experience on this and can give me some advice on that? If really cant,is there anyone who can provide me a battery backup circuit as well? Basically my project is almost the same as this.just the circuit is different..
  9. hi, i have a couple of question here.. Q1.may i know how we know the address of the message that we record in the ISD2548 chip? Q2.Can you all please tell me the maximum message which can be recorded into the ISD2548 chip?
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