RC India

Hi Guys,  :)

Iam planning to buy a multimeter to measure battery voltage. (I already have ordered a Turnigy wattmeter, so no need for it to measure watts.)

As of now I dont see any much use of it other than measuring battery voltages, But may be in the near future I will be using it If I assemble my own circuits. So any suggestions/Brand/Models :headscratch: to buy and what features I should look for would be relly helpfull.

As of now Iam looking for the ones that measure volts, Amps, resistance if possible capacitance.

Budget 500 to 1.5K :)

Thanks,
Vinay.

You will be able to get cheap digital multimeters for less than Rs. 200 from your local electronics market.

Well Iam aware of that, but I was looking for the ones that will be helpfull for electronics circutary as well. ANy model/BRAND that anyone has purchased, had experiance/issues with would be helpful for me to buy one. :)

Apart from having dedicated/standalone Tachometer/Thermometer/Volt-Amp-Watt meter its real nice to have a multimeter.

Though the decent/tack accurate ones like those from Tektronix etc cost beyond Rs 4K, more reasonable ones are  available in most local electronics markets (SP Road Bangalore, Gujraati Gali, Hyderabad, Lapjpat Rai Mkt/Nehru Place, Delhi.. rest find out  8-) )

We usually don't need real accurate ones, as accuracy of 1 decimal place (+-1-2% tolerance) are good to go. These could be easily  bought for Rs 600-1200 and make more sens to invest as you would sooner or later break them (put voltage when set on Resistance, drop, spill  etc). Remember, there are also Rs 150-200 ones available and they are better to avoid as they are quit nasty on reliability and accuracy.

I got this Chinese made, Indian branded Var Tech V92B auto range DMM which can do volts/resistance/amps/capacitance/temperate/continuity/audio freq/  for 650 bucks. its not way cheap,looks sturdy and gives accurate reading.


-Ujjwal

Where did you get it from?? SP road?

@TG, I bought it from OM electronics, which is one of the first electronics shop, as you enter into SP road (on the left). There are other options too who have even better range - like Vishal Electronics and few other Tool/machinery shops like HM tools, down the SP road itself.

Ping me if you need their numbers.

-Ujjwal

Authorized dealer for VARTECH in bangalore is M/s. Melody Electronics, Bangalore, S.P. Road

Reliability? A bit of a lottery, I agree but many work fine, without trouble. . Accuracy? Surprisingly good and perfectly acceptable for our kind of work/need.

At that price point one really can't complain.

As with most things in life, you get what you pay for.

I couldn't buy a DMM in my school days of electronics (4th class 1990) as DMM where way too costly then (may be 2K, socialist days of India). Later I smoked 3-4 of those cheapos (they still used to cost 400-500 back then) till college. They were cheap in all aspects - electrical/mechanical/finishing/Printing on panel. At least my new acquisition is much better than those, so fine with putting twice the money.

Hey Sushil! jealous of you man ... you live in Mumbai - Lamington Street there is Mecca for electronic components in India. Who knows you might get mine one there for Rs 200 only!


-Ujjwal

I'll goto SP road, find some brands and post before buying if I get confused for more suggestions.

I'm very happy with my Rs200 Mastech one bought from SP rd a few years back. Accuracy and reliability has been good enough for me that I rarely bring out my Fluke.

Make sure you check the prices in a few shops. Some dealers in SP rd are known to take people for a ride if they realize you don't have a good idea about the prices.

Thanks. Any shops you recommend?

Ujjwaana, would you consider that a "FLUKE"  ;D ;D

Funny name for something that is like the BMW of measurement devices  8-)

Need Advice...

Would a digital clamp-on meter be able to measure accurately the current thru each of the 3 wires of the Brushless ESC, when operating a  brushless motor. Put it differently, is the motor current reading accurate when measured by a clamp-on meter ?

No, that is not the right place to measure current with clamp meter. First of all the switching freq is way beyond what most clamp meters can handle. Also the waveform is not sinusoidal. You'll get much more accurate reading on the battery side with a DC capable clamp meter.

Can we not get a referral value so that if there is an increase or decrease in current one can understand the same from the readings. What I mean is something like this:

a. One measurement on one of the wires to the motor say we get a value of 22amps on the clamp meter.
b. At the same time when we measure with a proper dc ampmeter connected in series with the battery, we see a current of lets say 30 amps. This means 22amps read on clamp meter = 30 amps on normal ampmeter.
c. If I now increase the throttle, the clamp meter will show an increase to 28 amps when the actual value in the regular ampmeter shows 36 amps. This means 28 amps on clamp meter = 36 amps on normal ampmeter
Cannot this be calibrated thus to define values accurately?
Use of a clamp meter could also show if all three phases are supplying current equally or not for no change in throttle? (meanig possible detection of a cold solder or higher resistance in one of the phases)

If you calibrate for different loads like that, then it should work.

Small size digital clamp on meter with a max current reading of 600amps is only Rs.350.00 in the market. This I think, makes a handy tool on the field.

Question:::::
1) Do we really need a wattmeter?
2) If we need to measure battery voltage, can that not be done by the charger itself? I mean most of the chargers have a digital output screen to display the current volatage - AND we do trust this to be accurate to use the charger in the first place.

So my two cents (paise actually) on this is that most of the trouble shooting that we end up doing is just checking for continuity. This can be done with the cheapest of the lot.... what say folks?

Pankaj

Iam an HAM radio operator also ;D but as of now operating nothing, so in future If i build my own circuits I will need one. It will also be useful to measure any other voltage if required. So I thought some may have idea of whats good and bad in the market. :)

Yup we need to have a watt meter, if we plan to go electric, its just a safety device preventing burning of motor if we use the wrong prop. I plan to experiment a lot >:D

I am pretty sure people like Ashta would have strong opinions on this  ;)

If one wishes to continue with Electrics then one MUST have a Digital Wattmeter,a digital Tachometer, a 0-5Kg digital weighing scale which can measure in one gram increments, Thrust stand, a general purpose digital multimeter a 30-50 watt Hi Quality soldering Iron, Rosin Core Solder are essential. For the sort of work we do in RC a Rs.100-150, Wattmeter would do for general non critical measurements.   

hey what about a helping hand very useful when soldering wires,connector etc  ;D

Correction: in my previous thread read Rs100-150 MULTIMETER. Not WATT Meter in the last sentence.
and Yes a couple of extra hands would be really helpfull ;D

I have 1 multimeter which could measure duty cycle of pulse width moduled wave.
Could anyone knows bout it ?

just use voltage measurement

example :

if your supply is 5 v

- if it is 50% duty cycle - voltage will show 2.5V - simple !

Wow . Didnt knew that.
What  if the pwm is from a rc reciever

Pwm width from RC receiver is about 2050uS(max) and varies from 1000 uS to 2000 uS.So theoretically it has to work.