audioguru Posted January 2, 2007 Report Share Posted January 2, 2007 Hi Mandavar,Welcome to our forum. ;DA good place to find out about an IC is from its datasheet:http://www.datasheetarchive.com/datasheet.php?article=1131154 Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 3, 2007 Report Share Posted January 3, 2007 Hi AudiogururFirst of all thanks for ur greeting :DI tried to read the data sheet but for sorry it didnt help me i still cant understand how we can use this IC3 in such a operation...Is it possible to help me with the operation of IC3A and IC3b and the realation between them and the exernal connections... i really want to understand this.... Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 3, 2007 Report Share Posted January 3, 2007 Hi AudiogururI have another question about the circuit u implemented using LM2917 (14 pin) ..What if i want to use 9v (PP3 battery) the orginal one in the circuit? Do i need to change anything? If so plz can u help with this......Thanks in advance for ur helphave a nice day Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 3, 2007 Report Share Posted January 3, 2007 Hi Mandavar,The LM2917 has a built-in 7.6V zener diode regulator. A 9V battery quickly drops to 7.2V which is too low then slowly drops to 6V which is much too low. Some of the pins need the regulated voltage. If a low-dropout 5V regulator is added then the voltage might be too low for the IC. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 3, 2007 Report Share Posted January 3, 2007 Hi AudioguruThanks for your help again Actually i`m in need of your help again i hope i`m nt dist. you :)The first one about R8 What effect does this resistor for the signal when changing its value?The second and the last one about the Inverters (IC2) Why two of them connected in series (IC2b+IC2c) While the other three (IC2d+IC2F+IC2E) Connected in parallel?Thanks for your help Have a nice day Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 3, 2007 Report Share Posted January 3, 2007 The first one about R8 What effect does this resistor for the signal when changing its value?The DC output voltage of the inverter that feeds R8 is a little high, so reducing the value of R8 reduces its DC voltage which makes the inverters following it operate at their most sensitive voltage, and the LED will turn off if there is no signal.The second and the last one about the Inverters (IC2) Why two of them connected in series (IC2b+IC2c) While the other three (IC2d+IC2F+IC2E) Connected in parallel?The series inverters are biased so that they are linear amplifiers. The third one amplifies the output of the second one and the second one amplifies the output of the first one for very high voltage gain.A Cmos inverter has a low output current. Three in parallel have 3 times as much output current as one so they can supply enough current to light the LED, and still have enough output voltage to drive IC3. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 3, 2007 Report Share Posted January 3, 2007 Hi AudioguruI really want to thank you for your help againi really wonder if i can use a Buzzer in the load section so i can get a sound when the Input frequency is larger or equal to (1/2RC) and i need your suggestion about this if its possible...Another question about the (1000MicroF and 470 MicroF) Capacitors, why we are using this Values and why is attached in that postions the same question goes for the two Resistors Connected between pin[9 10 12]I`m really sorry for the amount of questions but i`m really willing to know and understand everything in this circuit becaues i`m intrested in it. Thanks for being so helpfull its so nice to get help from a kind person like you Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 3, 2007 Report Share Posted January 3, 2007 i really wonder if i can use a Buzzer in the load section so i can get a sound when the Input frequency is larger or equal to (1/2RC)The datasheet says the LM2917 can drive a load with up to 50mA.Another question about the (1000MicroF Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 3, 2007 Report Share Posted January 3, 2007 Hi AudioguruThe Capacitors are shown in the circuit u implemented using LM2917Check the Attachment the capacitors are shown below Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 3, 2007 Report Share Posted January 3, 2007 Oh yeah,1000uF across the car battery and 470uF across the circuit will filter out alternator whine and things that turn on and off like turn signals very well. I have some 1000uF capacitors that are quite inexpensive and are small. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 4, 2007 Report Share Posted January 4, 2007 Hi AudiogururAs i know the signal we want to sense its over/under frequency is the signal we obtain from pin 12 of IC2 and connected to pin 1 of (LM2917) my question why Connected pin 11 of (Lm2917) to the end of R5? What is the signal we obtain from the end of R5? Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 4, 2007 Report Share Posted January 4, 2007 R4 and R5 have equal values and are in series across the supply. Their junction is a DC voltage that is half the supply voltage and is used as the DC reference voltage for opamp IC1 and for the opamp at pin 11 of the LM2917. The output of the parallel inverters is also about half the supply voltage and is connected to the pin 1 input of the opamp in the LM2917 so it can amplify the signal very well. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 4, 2007 Report Share Posted January 4, 2007 Hi AudiogururI have another question about the Capacitor C2 that is connected to IC2A which has a feedback R7 does this makes IC2A a Diffrentiator and if yes what is the need of it?And another thing about capacitor C1 What is the main purpose of it?Really thanks for your help you are so helpfullHave a nice day Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 4, 2007 Report Share Posted January 4, 2007 I think C2 is to prevent the DC at the output of IC1 from affecting the input DC voltage of IC2.C1 is just a filter for the DC reference voltage. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 9, 2007 Report Share Posted January 9, 2007 Hi Audioguruyou told me before that the capacitors can filter out alternator whine and some nosie .. i just wonder how can capacitor do that? and does the filtration improves when we increase the capacitor value? i just want to know the realtion between the capacitors and the filtering thing and how it works..Thanks for your help again Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 9, 2007 Report Share Posted January 9, 2007 Hi Mandavar,A properly designed and connected car amplifier does not reproduce alternator whine.Its high gain circuit should be supplied with a filtered DC supply voltage. The filter is a resistor in series then a capacitor to ground at the amplifier's high gain circuit.A capacitor has "reactance" which is its impedance that depends on its value and on the frequency. A high value or a high frequency will attenuate the interfering frequency better. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 12, 2007 Report Share Posted January 12, 2007 Hi AudioguruI have a questions about IC1 (Diffrential amplifier) ..Is the same signal picked up by the sensor coil (inductor) entering the inverting and the non-inverting inputs of the IC1 if yes why is that?and in what mode this Diffrential amplifier is working (Common-mode??) ? Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 12, 2007 Report Share Posted January 12, 2007 The sensor coil develops a small voltage across it when it picks up a signal.The inputs of a differential amplifier are opposites. A signal between them is differential and is amplified. The voltage from the sensor coil is between the inputs.The same common-mode signal (interference) to both inputs is cancelled. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 12, 2007 Report Share Posted January 12, 2007 Hi AudioguruWhat effect does R7 do? why its used?-------------------------------------------------How can we describe by equations the voltage at Pin 2 & Pin3 of IC1 (Diffrential amplifier) ---------------------------------------------------Thanks for ur help Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 13, 2007 Report Share Posted January 13, 2007 What effect does R7 do? why its used?R7 biases the inverter IC2A into the linear region so it acts like a high gain linear amplifier.How can we describe by equations the voltage at Pin 2 & Pin3 of IC1 (Diffrential amplifier) Google has the equations. The gain is the ratio of the feedback resistors. Quote Link to comment Share on other sites More sharing options...
Mandavar Posted January 16, 2007 Report Share Posted January 16, 2007 Hi Audioguruin the operation description of this project the author write down that IC2B To IC2F (Cmos Inveters) do a clean pluse squaring to the signal. my qustion is how by inverting a signal we can have a clean pluse squaring operation?And does these inverters further amplifiy the signal besides the inverting?Thanks for your help again Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 16, 2007 Report Share Posted January 16, 2007 in the operation description of this project the author write down that IC2B To IC2F (Cmos Inveters) do a clean pluse squaring to the signal. my qustion is how by inverting a signal we can have a clean pluse squaring operation?And does these inverters further amplifiy the signal besides the inverting?A Cmos inverter has a gain of about 30 with a 9V supply voltage. This circuit has 4 0f them cascaded so their total gain is about 810,000 so a tiny signal at the input causes the last few inverters to produce clean saturated square-waves.Here is a graph showing that the gain of a Cmos inverter depends on its supply voltage: Quote Link to comment Share on other sites More sharing options...
theglobe Posted April 24, 2007 Report Share Posted April 24, 2007 How can i modify the speed-limit alert circuit by using the speedometer itself as a sensor instead of using the miniature inductor??? Quote Link to comment Share on other sites More sharing options...
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