[what should i do about computer rf emissions?]

Hi
Take radio to a better location not in in vicinity of TV or computer or any device using SMPS and crystal oscillators.

[Could somone tell me what this is?]

Hi
This is rightly said to be a mutual inductance demo kit

[Need advice on equivalent transistors of: SL100 and BC158A]

Hi HERCULES
welcome

BC158A cPNP transistorv an be substituted by 2n2907A taking care of the pin differences

SL100 is a medium power device, and if from india, you get CL100, BEL100N

otherwise, you may perhpas try BD115

[0-30 Vdc Stabilized Power Supply]

congrats

please post a photo of the pcb assembled by you as .jpg

[What shottcky diode do I use?]

the voltage drop across highspeed diode is more than that of a schottky diode
the working voltage ,if it is less , we will be adding further voltage drop, thereby reducing the voltage to the actual load. that is why perhaps they prefer to yuse schottky device.

[What shottcky diode do I use?]

Hi
you could use  say IN5819 series.

[Electronic Stethoscope 2]

Hi

Recently I saw one circuit of steth with pizio buzzer element (two tagged) as sensing element.

[Need RF transceivers in PDIP or DIP]

I need a RF transceiver operating in the ISM band or so, for local data telemetry using FSK or ASK, in a DIP or PDIP form, that i can request as a sample(i.e. for free).. Any ideas? I know it's cheap of me, but in India, component availability is very suspect. Please help me guys..

Hi
try www.sunrom.com
they offer STT and STR 433 a set . in Indian Rupees and at $ rates aswell

[ATTENTION: Illegal content (ebook/magazines/software) will be deleted]

Hi all
let us honour the rules of the site and also protect the MAGs' rightseven-- afterall it will cost us few bucks prchase-- imagine a robbery inour own homes??? pity

[For fun - What is your degree?]

Hi
even for FUn to expect reply from 25000 appox  membership -- think of what are you expecting  from this form with HUGE membership-- an impossible task and this site will be filled up for nothing but so called fun-- good  i am also on  power electronics while worked for telecom.--

[Psophometer Level Meter]

Hi cynicmonster
welcome

please download and see this pdf 

you will surely be enlightened

www.audioprecision.com/bin/AMH-1.pdf

check for psophometric weighing etc

[free energy motor]

Hi Indulis
i had recently visited an enrgy saving exhibition at Hyderabd, wherein M/s NMDC (national minaral development corporation), participated --which enthused me to probe their participation cause--

they have apeculiar cituation and use it to regenerate power and they gave a brouchre

it is rather dificult o post it here -- but i suggest you to see their website
their regd office is located at Hyderabad -India


www.nmdc-india.com

[Help required with switching problem]

Hi
try IR LED and Photo tranasistor on either side to sense the car passing thro breaks the light path --use thr Transistor outputs to trigger set / reset flip flop

-the output could drive a relay with change over contacts to reverse the power to the motor

[Electronics kits...]

Hi
audioguru is right in saying not make CHEAP kits. in general many kits are costly perhaps due to limited volumes sold, as compared to finished products.

members prestigeous fourms like e-lab.com shold comeforward to be able design and realise instead of ckd or skd assembly.

Here also, as Audioguru once put it -- we will be able to assemble but not give a finishing to it with a proper cabinet or a housing.

If these are done for the sake of experience(hands on ) then the extra cost is worth it as person gains practical knowledge which will be a factor to deside his/her future.

[Frequency Division]

Hi
such nice info (thanks Hotwaterwizard)  i do recollect my training days.

perhaps the clock being 4MHz, even CD40 series (CMOS)can work and with llower power consumption. ofcourse the proper pin outs shold be followed.

sarma

[CRT monitor pinouts]

PLEASE TRY THIS Color VGA Adapter

Pin# Label Function
1 RED Red color signal
2 GREEN Green color signal
3 BLUE Blue color signal
4 ID2 Monitor identification bit 2
5 N.C. Not Connected
6 GND-RED Ground Red signal
7 GND-GREEN Ground Green signal
8 GND-BLUE Ground Blue signal
9 N.C. Not Connected
10 GND-SYNC Ground Sync signal
11 ID1 Monitor identification bit 1
12 ID0 Monitor identification bit 0
13 H-SYNC Horizontal Synchronization
14 V-SYNC Vertical Synchronization
15 N.C. Not connected


SARMA

[CRT monitor pinouts]

HI
FOR EXAMPLE A VGA MONITOR BY DELL HAS INDICATED IN THE SITE BELOW
http://support.dell.com/support/edocs/dta/NL25/00000005.htm

PLEASE TRY OUT

SARMA

[SMP power supply]

hi
the circuit shold have been shown fully instead of masking valid portions-- thus it appears deliberatein the sence, it may perhaps be a question in an exam? right!!

the dual caps and ajuper near the bridge provide forchange over between  two versions of incoming AC Supply -- like 110 V/60Hz of Japan, US, even canada if i am right; while 230V/50Hz in most other countries.

Others Qs are to be thought over

sarma

[Convert 6VAC to 12VDC ?]

Hi Covalier
First convert the 6V AC to DC , filter it
Then use a MC34063 ic with few other components in a boost mode to say 15V DC
Have an additinal filter for reducing harmonics.

12DC is ready

see the datasheet attached

All the best

sarma

[Two 7490 to 74390]

hi
do you really need to substitute-- why not, if possible original 74390 or 74ls390

if need to do.

make a small adopter board with berg pins at the botom to suite t4ls390 pin ot and put 2 nos 7490 on topnear to the pins and try hard wire.. -- laborious job--

sarma

[plz help urgently]

Hi
audioguru is RIGHT
the IC is quad opamp

sarma

ps thanks audioguru

[plz help urgently]

Hi
please see any datashhet for LM324

it an ic with four similar circuits called comparator.

each one can compare two input signals and out put a +ve voltage or a near earth depending on the comaprision. this just in plain english approximately. for datails see the datasheet  at sl No 12 at
http://www.electronics-lab.com/downloads/datasheets/ic_analog.html

sarma

[Need to design a filter to allow only voice frequencies]

Hi
perhaps the attenuation out side the audio band  depends on the % tolerence of the components you use across the filter like the one suggested by Audioguru

Try toassmble one and  run a test with a set of frequencies,say , from 200Hz to 4 or 5KHz  and tabulate you will know the filter behaviour. 

you may have the set up at any lab near to you.

sarma

[Resonator datasheet needed]

hi Hotwaterwizard

SO NICE A Resonator
like to see it in 4th dimension--(i mean some one performing on it

sarma

[Motorola's circuit doesn't work.]

hi Mic3ca
whynot keep diode series to the resistor while reducing the 100k to say 1k as it is for base current limiting and the series diode can effectively block the -ve signal from RS232. ofcourse you could terminate the base with say 100K

sarma