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i want to use 8870 in my project my project requires an output voltage of 5v from 8870but output which i am getting from 8870 is 1.70v.i have 741 ic amplifier but dont know how to use it.can you please help me in finding the reason for low output voltage?
Hi,Quote from: angad on August 23, 2011, 12:48:15 AMi want to use 8870 in my project my project requires an output voltage of 5v from 8870but output which i am getting from 8870 is 1.70v.i have 741 ic amplifier but dont know how to use it.can you please help me in finding the reason for low output voltage?How should we be able to, when you post absolutely no info on what you've done, no schematic with component values and no nothing at all?The 8870 gives (close to) 5V out when driven from +5V, so either the 8870 is dead, you didn't use 5V or you messed up something else, but that's as close as we can get without any info.If you don't understand a single op-amp, then how do you dare hoping to understand a circuit that contains so much more than a couple of op-amps?Op-amps are fairly simple. their entire purpose in life is to keep both their inputs at the same potential and it will change its output to achieve that if possible (or hit the supply levels trying).You can find lots of tutorials on op-amp circuits on the net.
*Reviving Topic*I have some time on my hands , would anyone be interested in a short tutorial on using 8870 DTMF Decoder ?
i want to operate an 4 wheeler robo using mobile phone's dtm frequency i have checked my 8870de as well as ckt connections i m getting correct output but it is low in voltage example on pressing 2 from mobile phone i m getting output at correct pin but its voltage is low
and if i use op-amp it make robo less mobile as it require an input votage of 12v which i have from adapter only this would make me use 4 adapter
i will post ckt dia soon as i ve met with an accident last need 2 week 2 recover i ve plaster on my right hand. need urgent help minor project need to be submitted next month .
Hi,Quote from: angad on September 12, 2011, 03:31:22 AMi want to operate an 4 wheeler robo using mobile phone's dtm frequency i have checked my 8870de as well as ckt connections i m getting correct output but it is low in voltage example on pressing 2 from mobile phone i m getting output at correct pin but its voltage is lowSounds like you forgot to pull pin 10 high?Quote from: angad on September 12, 2011, 03:31:22 AM and if i use op-amp it make robo less mobile as it require an input votage of 12v which i have from adapter only this would make me use 4 adapterI doubt that you'd need an op-amp, but even if, you can get op-amps working down to under 1V supply voltage and transistors is yet an option.But do connect pin 10 to logic high to enable the internal pull-ups.Quote from: angad on September 12, 2011, 03:31:22 AM i will post ckt dia soon as i ve met with an accident last need 2 week 2 recover i ve plaster on my right hand. need urgent help minor project need to be submitted next month .Test this and post back if it still acts up and drive (more) carefully
Does anyone knows how to reset the output pins?? please help as this is the big problem i am facing.for example, the output pins should remain high till the button is pressed, but actually output pins remain high even after button is released.
I have connected the pull down resistor as you told, but still it is not working.I have connected the circuit as shown in the attachment. I am using CM8870 DTMF IC...