Sukhbinder

Hi aniruddha, what are you up to man, when dealing with polarized caps always keep the polarity in mind and the maximum voltage rating also. ( if connected wrongly or the voltage exceeds the rating, the capacitor can burst and giving off quite a nasty smell). Electrolytic caps have a tendency to dry out with time raising their ESR (Equivalent Series Resistance). An old Electrolytic may not show much drop in its capacitance but the ESR goes up quite fast. To check the ESR you need an ESR meter , a Capacitance meter will not work in this case. If you are simulating your circuits on a PC using softwares like Electronics work bench, Multisim, or circuit maker, never rely totally on the softwares. As per my personal experience these softwares work well for digital circuits but not for the Analog circuits. So stick to the old breadboards to get the best results. ;)

Thanks ;)

Hi chi_visor, where do you put up in INDIA? I also live in INDIA. i'm putting up in New Delhi. As audioguru suggested it would be better to buy a MP3 to radio transmitter. i got one for myself from Lajpat Rai Market for Rs450/-. it uses a single AAA cell for the power supply and has a stereo pin as the input. just plug it in the headphones jack of your PC or any other player and you have 4 different frequency setting to chose the transmitter frequency. just tune in your music system's tuner at FM band to the frequency and enjoy the music. i checked it and it transmits in stereo. I opened it to check the components and it used just 2 ICs from NJRC (don't remember the numbers now). its the most simple way to connect and MP3 player to any system. by the way i got this from a car audio dealer, great to hear MP3 music on your old car audio.... ;D

Thanks for the help. one more query, the Pal007A is a 4X50W Mosfet IC while the TDA7560 is a 4x45W IC. i checked up the pioneer website, even they donot have a datasheet for the PAL007A listed there and in their parts section the PAL007A is replaced by the PAL007B. ;)

anyone having the data sheet for the PAL007A power amp from pioneer corp. its a 50Wx4 BTL amp from the KEH-P4025 car audio from pioneer. ???

Thanks for the service manual Hotwaterwizard ;)

Thanks this does seem similar to some extent but i still need the 4020 service manual. ;D

Hi any one having the Pioneer KEH-P4025/4020 service manual. the 4025 has the same manual as the 4020. please post it if anyone has it. thanx ;)

You may try out an PC power supply. u can get one quite cheap these days and they provide about 25-30A at 12V depending on the wattage of the supply ( u can have a 400W supply for a home PC or a higher one used in servers) u may need to connect some load to the 5V output of the supply also as some supplies do not work well without it ( try installing some cheap cooling fans or some LED lights to the 5V supply, maybe it will work out well) ;)

Thanks for the replies guys but i'm still in the dilemma that why the 3dB spec only. Leaving aside filters, there is a cutoff freq for a device also (say a transistor). any body having any idea about transisent time concepts. i know these are the fundamentals but they are never thought in our courses as they should have been. we are more focussed on the applicationa than the theory behind it. ;)

What is the logic behind the cutoff frequencies being defined at the 3dB points? why do we use the 3dB points only. is there some thing to do with transient time? these are some things we all study in our courses but what's the basis of these concepts. any one who can explain these basic concepts which we use everyday. ???

any one having Sony CFD-F17CP Schematic & Service manual. thanks in ;)advance

The TDA1524A IC is a bit fussy when it comes to performance, i once tried making the circuit given in the datasheet. it worked fine with my HA1392 based amplifier but didnot work with my STK465 based amp. the bass corection network works great and the contour setting settinh really works. there is another alternate to the TDA1524A from national semiconductors, its the LM1036 Dual DC Operated Tone/Volume/Balance Circuit. it works similar to the TDA1524A. ;)

thanks for your idea but i don't think that it is an scr. i can't see a diac or so connected, all i see is a 7.2V battery connected through a trigger button ( which itself regulates the speed of the motor). the transistor is connected to the trigger button and the trigger button assembly also has a polarity reversal switch so that the motor can work as a screw driver also. maybe i'll try out the TIP127 darlington PNP transistor, it can handle curremts upto 5A

generally all IR diode packages are made such that the field of emission is limited, a lens may help collimate the beam but won't improve the range much. to improve the range u'll need to use two IR diodes. ( as seen in some older TV remotes, it improved the range and also the field of emission so the remote could be used from different angles from the detector) ;D

use the equation R=(Vcc-Vled)/Iled. Vcc is ur supply voltage, Vled is the led forward voltage drop (usually 2-2.2 volts for green leds), Iled is the green led current u need (check up its data sheet for the recommended value, usually normal leds work at 2-5mA and high efficiency leds can work at 10-20mA). i suggest that u stick to the phototransistor as its easier for u to use. a photodiode is connected in reverse bias with a limiting resistor, it works best with a pulsed signal but it cannot give enough current to drive ur LED. a photodiode must be used with a buffer circuit to boost the current (or u may say that the diode is the sensor but the transistor can act as a switch). the advantage of a transistor is its higher current switching and higher sensitivity but it has a lower bandwidth (upto a few hundred KHz) while a diode has a very low current but has a very high bandwidth (few MHz). u can also use the IR detectors used in the TV remotes like the TSOP1738, u just need to connect to Vcc and ground and the 3rd pin for the o/p goes low when it detects an IR signal. u can connect a transistor to invet its output and drive the LED. u'll need a pulsed signal at about 38Khz for the transmitter. here is the data sheet for it check out its detection frequency range TSOP1738.pdf

thanks for the links, but there is still a problem, the FZT951 is an SMD transistor and the 2SA514 is a TO-220 style transistor, i don't think that the FZT951 can handle the current to drive a 7.2V motor in a cordless drill. maybe i'll look for a substitute in the TIP series on pnp transistors. can a MOSFET be used in its place?

Hi vbSteve, wellcome to the world of electronics, its not too difficult to learn electronics, if u know some basic hardware concepts well then with ur current knowldge of C++ and VB things will be piece of cake. back to ur query, u said that u have a three terminal photodiode, well in ur case u must be refering to a photo transistor as a diode (di= 2) is a 2 terminal device. a photodiode is used in the reverse bias mode and when IR light falls on the junction minority carriers are generated which cause the diode current for detection. a photodiode will work in any visible wavelength also but the case is made such that it filters out all radiation except IR ( this prevents the device from being activated in ambient light). u are using a phototransistor which is like a normal transistir except for the case that it is switches on by the light and not the base current (u may have a little base bias to allow for proper switching. u can connect the green led between the phototransistor emitter and ground. and remember to connect the phototransistor collector to the positive supply through a current limit resistor. when the IR falls on the phottransistor it will switch on and start conducting and the LED will glow. ;)

Hi guys, i have a cordless drill/driver (make TGF china). it uses a transistor to control the speed of the drill/driver along with the trigger control. th emore u press the trigger the faster the rpm. the transistor is a TO-220 style package with A514 written on it (which i presume is 2SA514 as japanese transistors are usually named). any one having a its datasheet. i need to know how much power the transistor can handle. the power supply of the drill is from a 7.2v NiCd battery (6x1.2V cells each rated at 1200mAh). thanx ;)

Hi mvs sarma, your are right the TDA2822M is a very versatile IC and i've seen a number of computer multimedia speaker brands in INDIA which use the TDA2822M as the main power amp. although its rated as a 1W/ch IC the speakers show a rating like 220W PMPO (this PMPO thing is all rubbish, never go for the PMPO rating always check out the RMS ratings for amps, by the way PMPO ratings are not recognised as a standard by the electonics and electrical engineers). i had seen a 2.1 speaker system which uses a TDA2822M for the satellites and a TEA2025/KA2206 in bridge mode for the subwoofer. quite a small and cheap contraption but works well for low budget needs. ;)

i once read about the LM390 which is a low voltage high power amplifier. i have not myself used it but it may come in handy in this circuit. i've used the TDA2822M and it works well. i had made a small amp for my walkman using the TDA2822M driven from 4.5volts (3 AA batteries), well if u use small speakers then the quality is good and u won't find much distortion. i leave it up to the user and other senior members to decide which will be better. ;)

Hi guys, if u can do away with the LM386 i suggest the use of the TDA2822M. it is a 8 pin dip ic working from 1.8v to 15v and gives an output of 1W/channel ( its a sterao amp for low voltage devices). it uses minimal components and can be used in bridge mode also. here's the data sheet for it TDA2822M.pdf

A bridge rectifier as the same ripple factor as a full wave rectifier. however it is easier to use as it does not require a centre tapped transformer. very usefull for converting 220V AC mains to DC ( as in Switched mode power supplies)

i both agree and disagree with audio guru about the advantage of a 2 diode full wave rectifier over a 4 diode bridge. a 2 diode rectifier does have a lower forward volatge drop but the diodes must have a higher PIV rating. lets say we have a 60v ac input. in a 2 diode full wave rectifier we need a diode with a PIV greater than 85V (60xsquare root(2)), so u use a 100 PIV rating diode. if u used a 4 diode bridge circuit, the 85 volts are divided between the two series diodes (42.5 across each) so u can use a 50V PIV rating diode. a higher PIV rating diode will cost more. However these days as the diode costs are quite minimal u can always use a bridge instead of a 2 diode full wave rectifier due to some of its benifits like 1. u donot need a centre tap transformer for the bridge. 2. can be used on DC supply also for polarity protection. 3.dual power supplies need a centre tap tranformer and a Bridge rectifier. 4. if the transformer taps are not balanced (i.e. u have a 12-0-13 instead of a 12-0-12 transformer ( low quality transformers) the there will be a ripple of 1 voltage in the final dc voltage which degrades the power supply. with a bridge rectifier there is no such problem. 5. the low cost of commercially available bridge rectifier modules has boosted their use.

Thanks for you help audioguru. i happened to have a chinese made FM mic with receiver and found the receiver using the CXA1191. the mic is copy of the FM mic made by philips. i'll check out if the CXA1191 is available easily or not