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mvs sarma
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Posts posted by mvs sarma
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Hi AN920,
Thanks for such nice review and critical observations. In fact i have made the PCBs locally and just abt to assemble. -your comments are just useful.
the 47pF cap across collector and base of darlington , if it could be shifted to base to earth of the same device, will it suffice without need to discretizuing the darlington?
please comment.
Sarma -
Hi
please see this site
http://website.lineone.net/~harrison.elec/manuals.htm
Sarma -
Hi Walid jee,
So Nice that you have taken my thoughts to 1960s- when we just entered Telecom service and were undergoing training- we has chance to get library access to see latest MAGs like Practical Electronics, Popuplar Electronics, Wireless Worls, It is Nice to see Practical Electronics kicking well evenafter 45 years. we used to get periodicals like ETI autralia, Electronics Autralia, On the communications front a munufacturer Eenkurt used to publish and distribute free monthly issues under the name 'Lenkurt Demodulator' an informative and small booklet covering various topics.
Now a days you also see mags like Circuit Cellar, EPE Mag, Elektor-electronics, most being a mix of Software & Hardware
Thanks agaian
Sarma
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Hi Thomas,
Nice outcome for the effort put in,
Siiting here in India, I really love it.
All the best and wish you best future in your personal professional life
Sarma -
Dear Mr. SVS Sarma,
I am very much thankful to you for the reply. I am at one with you. Accordingly, I have searched everywhere on the pcb or at the backside, but in vain. However, I can tell you that the radio section used the following ICs and I have already downloaded and have with me the datasheet. What i need is the functionality of the whole operations of selector mode switch, which only i can have it on the whole schematic.
The Circuit uses the following ICs in radio section:
LA 1185 + LA1260
BA 1332
Main AF Ampl: uses BA5406
I doubt whether the selector switch (Radio/Tape/Sleep) or band switch (FM/MW/SW1/SW2) has gone bad.
Are you staying at Banglore?
Please also advise where could I have the same and in which book, as you specified which is available in BPB publications. Since, you also belong to India, can u please help me. However, I am ready to pay for all that.
Thanks and regards,
Shamim_India.
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please see the photo whether RX 5030 tallies
Sarma
at Hyderabad
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Dear Mr. SVS Sarma,
I am very much thankful to you for the reply. I am at one with you. Accordingly, I have searched everywhere on the pcb or at the backside, but in vain. However, I can tell you that the radio section used the following ICs and I have already downloaded and have with me the datasheet. What i need is the functionality of the whole operations of selector mode switch, which only i can have it on the whole schematic.
The Circuit uses the following ICs in radio section:
LA 1185 + LA1260
BA 1332
Main AF Ampl: uses BA5406
I doubt whether the selector switch (Radio/Tape/Sleep) or band switch (FM/MW/SW1/SW2) has gone bad.
Are you staying at Banglore?
Please also advise where could I have the same and in which book, as you specified which is available in BPB publications. Since, you also belong to India, can u please help me. However, I am ready to pay for all that.
Thanks and regards,
Shamim_India.
Hi Shamim jee,
As you rightly told the wires comming from the radio-tape sleep switch can be traced and (thinking that battery is switched) the radio position wire coud have been wrongly placed by any other service or by the owner- by mistake. while the sleep wire will go to the Tape motor.
So I feel if you trace with a Multimeter the voltage on the Vcc pin of radio IC wet ground- and see the correct location of the wire coming from the radio-tape-sleep switch.
In case a flat cable is hand wired or plugged from the switch concerned, --there may be a wire loose conn or print break just below the concerned wire.
we may have to handle the situation coolly by considering a nearest comparable schematic--
now that you have told the ICs used let me see--
sir appearantly , how old is the 2 IN one?
you cam mail me also
Sarma
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On the PCB or somewhere you are likely to find model number-
otherwise, a set of radio and tape recorder circuit books are sold by M/s BPB in india and they used to have a shop in MG rad Bangalore.
alternately, the local Panasonic service centre at bangalore(bangaluru now) can perhaps handle the item for you
Atleat you might put a photo how the item looks like to be able to know its model number.
Sarma -
Hi,
As some one said, enter the dragon may be easy, but managae and retreat is and will be a problem
Same will be the case with philipsTV
Evenif i could tell you how to enter , you require the data for seeting things over there-- any disturbance- you may not be able to work the TV to what it is a moment back--
So i suggest to try and get service manual for the set you hold. and thereafter things will be better and you may go ahead confidently
Sarma -
hi,
I need some program that it draws PCB circuits...
plz help me..
I can't find anything that I want! :(
THANKS!:D
The programs won't generally draw PCBs-- we the humans use the program to help drawing the PCB layouts. Even auto routing will disappoint unless the components are intelligently placed.
as a beginner you may find it hard-- it was hard to take food even unless parents taught us-- put little more interest and you would enjoy-- also try PCB123 software- it is free download - you may google for it. and the firm will be happily giving you finished boards if you forward the layout to them at some nominal price.
All the best
Sarma -
Hi Walid, i have a doubt on the schematic put up- there has to be another transformer to recover the 455Khz IF after the osc coil.-- in fact the primaries of Osc coil and part winding of 1Sst IF (yellow Generally) wiil be in series. the secondary of this yellow device will give you 455KHz--
other calculations you are discussing with AN920 , i shall be watching curiously Sir,
regards
Sarma -
Is it worth it to pursue a career in electronics these days?
With the outsourcing and disposable products,
hands-off management positions and so forth.
Or is it better left to the hobbyists?
Why to feel like thaat/ general priciple in outsourceing is not to get bogged by repititive work-- you can always take up a front end researchand comeforward with newre and latest designs-- you may revise old sesigns to be cost effective-- one has perhaps to be resourceful in his/her thoughts ang life is always encouraging--
Once you feel awalk of life is getting blocked , we can imagine that yet another new door is opning up for electronics of for that matter any curriculum.
Sarma -
Ofcourse, ther is another way- if you don'et want to use 5V at all
the principal controll circuit regulating 5V, can be modded to control 12V instead of 5V. then the artifivial load on 5V can be avoided.
Sarma -
Hello,
I have searched all search engines and can't find an answer to my question.
I have a Panasonic SL-SX480 portable CD/MP3 player that is DC only. It takes 2 AA batteries (1.5v for a total of 3v).
I added an AC power input jack by soldering the wires to the positive and negative DC power points on the circuit board (where the batteries connect).
I used a wallwart converter; the CD player wouldn't work at 3v, so I moved the switch to 4.5v and it works fine.
The problem is that now, it won't work with batteries anymore. I have thought about making a battery pack using three 1.5v AA batteries and plugging it into tho AC power input jack I added, but that would make it not as portable as before (if it'd even work).
How do I get the CD player to work with batteries again, and still keep the AC jack?
Sincerely,
Mike C.
you use a break type jack --when you unplg the adapter (wallwart at 4.5V DC), the internal batteries should connect thro the contact. this techniques is used to cut off your speaker when you plug earphones.of course it is on audio output. same phylosophy can be follwed atinput supply also.
Sarma -
Hi Shamim,
i fear you won't get -- you may have to purchase.
I remember at Chennai- book shops in electronics spares market sell diagrams in multicolor.
for eg.eletek books and kits is one source at chennai. -
Hi,
try here for alphaneumeric codes.
http://www.tkb-4u.com/code/smdcode/indexsmdcode.php
reg color codes, i feel normal codes do work with smd even if used
however, the manufacturer concered can be googled for specific needs
Sarma -
Guy A claims that I must not leave my computer turned on overnight, as a friend of his did that one time and his house burnt down because of it.
Question: If I leave my computer on for days and days, can it cause a fire at some point, and if so, under what circumstances? Take into consideration even the extremes, but also note that there is no living being next to it at any time.
I'm not an expert in electronics but my common sense and the years of leaving my computer on 24/7 without any misshaps makes me think such thing is at most as possible as a meteor hitting the earth.
Thanks in advance
Please accept the truth-- any malfunctioning equipment -- need not be electronics or computer related-- CAN BURN A HOUSE DOWN--
FOR EXAMPLE
GAS STOVE WITH LEAKING HOSE or with a forgotten open valve
STOCKED ETHENOL OR PETROL IN NON-STANDARD FASION
UNCHECKED ELECTRICALL HEAVY DUTY SOCKETS AND APPLIANCES
HALFBURNT RAGS LEFTOVER.... THE LIST IS ENDLESS.
a bottle with alcahol leftover
we do require caution
Sarma -
It is OK.
do you find regulators inside or voltage stabilisation using zenor diodes? f so what is / are the regulator(s) / zenors used?
Incidentally you never indicated the make and model Number of the equipment under reference.
perhaps a replacement Tranformer is much cheaper compared to total equipment -- unless the said equipment is very much old-- then better to change-- while so, better go for modern 5.1 audio systems and try covert all your casttes to CDs progressively.
Sarma -
My audio equipment burnt its transformer. .........
Basically you may have to study the other circuitry and the audio eqpt specification from the user manual.
1. whether input is 230 or 110V-- depends on your location.
2. you have two options. a. get it wound as it is by a local winding shop/repairer.
b. do it yourself.
If option is (b) , you have to count the secondary and primary turns while ripping it and Try to duplicate.
If you know the seconday voltage, as per the electrolytics, i cold feel that secondary may be 15 to 18V or 20V at the wiorst.
But you can't take chances, lest you may end uploosing other parts.
By any means , it appears to judst duplicate it by careful reverse engineering.
Even if the primary is partly burnt, at one place the wires may be jammed, it is still possible to be able to count the turns while ripping.
FInally, if the make is known, transact with the manufacturer and seek a replacement transformer or the tranformewr data-
Some times if you have a service data you may know the unregulated dc a\oltage and even the secondary AC voltage. if so you could improvisea substitute for it.
All the best.
Sarma -
Hi,
Why not try ULN2003 or ULN 2803 interface chips instead of discrete transistors.
Sarma -
Case.1
You try TRIAC control on primary with ofcourse suitable line filteres to meet local regulatory needs.
then see that the output is stepped down to 12V. I feel this concept should serve your needs.
Case2:
you try to have halfwave rectification and try to regulate with nominal filter. then the output voltage should fall down. this time you may neeed higher power diode to supply larger average current in the absence of second halfwave.
Case3:
ypu go for non isolated dc-dc converter to convert the rectified 19VAc (may be around (1.4.14*19V)-2*diode drop
as the supply is already isolated you dont need another transformer. a high current Frerrite inductor will do.
Sarma
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Kevin
No!!! A DC-DC converter has a DC primary. You've never heard of a "off-line switcher"? It's still a DC-DC converter on the back end with a AC-DC front end. What do you think the power supply in your computer is??
perhaps one may not call it smps, but Triac (primary comtolled) AC-DCconvertes are not unpopular. may be the type of technology was used for battery charging.
Sarma
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Hi,
I'm a software engineer that has some electronics ideas and I like to build some prototypes.
Does anyone have any suggestions how I can find someone to do it?
First project is a voltage regulator for automotive alternators...I want to generate 72vdc or more rather than just 12vdc.
Thanks,
Danny
Hi Danny,
Now adays experts of your status, should, ifeel, not confine to a cornerof software--
for example, i know of my co-brother whis a doctorate in chemical technology and equally good in electronic software and even hardware. Medical professionals are practicing not only medicine but also electronics to make their analysis and test procedures simpler.
As a pasttime , i sincerely feel thaT YOU MAY BE ENTHUSED TO REALIZE YOUR IDEAS IN 3dBY YOURSELF AND I AM SURE , YOU WILL BE DERIVING GREATER SATISFACTION.
nOW A DAYS IT IS NOT DIFFICULT TO FIND A INSTITUTIONknoWN TO YOU WHERE THE students are craving to do projects. you could perhaps be a guide to them and it serves dual purpose.
Sarma -
Aniruddha may appreciate that auto routing is NOT that effective unless the placement is opimum and the the software is really a wothy type. But again such items are obviouly priced HIGH and perhaps only High volue users and Idustries only can afford.
One must accept that there is nothing to beat HUMAN BRAIN.
Asd such we should leave the dream for auto routing (efective) be done with semi auto and manual methods. -
Hello friends,
Initially I have to convert the 24V signal to 5V which I did using voltage divider circuit but now the thing is my input signal level is not decided it may vary from 15V to 24V so the question is how can I maintain 5V.
My input is varying from 15V to 24V but I required 5V output.. how can I do this??????????/
;D
you didn't mention how much current you want to draw at 5V --neither you mentioned whether it is DC or AC-- i
if Dc you want large currents use 7805 with adequate Hestsink.
if dc and for very small currents like less than 5 mA use a high watt (2watts)resistor of say220 ohms and a 2 watt zenor diode of 5 V or 5.1V (generally available
if it is AC power you have to adopt different techniques.
Sarma
Micro FM TX (Micromitter)
in Electronic Projects Design/Ideas
Posted
Hi,
Nice analysis AN920.
Fine i shall be using your suggestions . Nice of you and thanks for a timely coincidental help.
Regrads
Sarma