Necessary Equipments needed for SMPS development.

[MicrosiM]

Since there will be some DIY SMPS projects in here, or may be at any other locations.

I wrote the below paper for the DIY people, In order to help them making there own SMPS, while following some safety procedures.

The paper talks about Necessary Equipments needed for SMPS development, :x: and some warnings you should be aware of. :x:

Other papers will be launched soon.

 

[chaudio]

One of my recommendations if you're going to be working on SMPS is a differential scope probe. I don't think the 'floating' oscilloscope is a good idea. When trying to look for example at the gate drive on a half or full bridge design, the only way to do it is using a differential probe.

 

[CobraNet]

Price

One of my recommendations if you're going to be working on SMPS is a differential scope probe. I don't think the 'floating' oscilloscope is a good idea. When trying to look for example at the gate drive on a half or full bridge design, the only way to do it is using a differential probe.

I dont think that any DIY will be able to afford the price of that differential probe.

http://www.tek.com/products/accessories/differential-probe.html

As an example, GDS2000 Scope price about 1000US$, and probe is about 1300US$.

It depends on the budget...

 

[chaudio]

Personally I use a much cheaper add-on differential probe: http://accessories.picotech.com/active-oscilloscope-probes.html#TA057

While it might not be as accurate as a Tektronic unit, it's certainly very useful for what I do, which is mainly amplifier repair. Can also be used for measuring the output of bridged amplifiers which is very handy indeed.

Incidentally the Tektronic probes you mention above appear to be more designed for probing differential data busses etc, not for high voltage use.

 

[CobraNet]

Personally I use a much cheaper add-on differential probe: http://accessories.picotech.com/active-oscilloscope-probes.html#TA057

While it might not be as accurate as a Tektronic unit, it's certainly very useful for what I do, which is mainly amplifier repair. Can also be used for measuring the output of bridged amplifiers which is very handy indeed.

Incidentally the Tektronic probes you mention above appear to be more designed for probing differential data busses etc, not for high voltage use.

I dont think its cheap either! 30% of oscilloscope price.

DIY cant afford it, many people using X100 probes without problems.

 

[chaudio]

Well it was only a suggestion! Personally I've found it's one of those items where I don't know how I managed before I bought it and I thought I'd share that.

 

[CobraNet]

Thanks

Hey..

I didn't mean any thing, I used X100 Probes before to repair some SMPS in the past.

Thats why..

 

[jade_808a]

Hi,

I am new here, I have seen some really old TV techs here in the Philippines that have converted some old B/W TV's into an "oscilloscope" well its not very high tech, but it enables them to see if there is an oscillation or any drive signal from any switching circuitry, I wish I was that "old" he he he he. They are very resourceful. I am glad I have an 50Mhz oscilloscope.

Regards,
Jade

 

[krisfr]

I have seen and worked with 110 volt smps, so why are you saying only 220?

 

[MicrosiM]

220

I have seen and worked with 110 volt smps, so why are you saying only 220?

All details in the paper, applies to 110VAC or 220VAC SMPS designs, since the 110VAC design will use a voltage doubler.

 

[sphinx]

I find a variac helpful for testing my smps at lower voltages first and to check UVP and OVP. A solder pot helps to remove wire coating when building transformers and inductors.

 

[lorylaci]

I built my first SMPSs with a 10Mips digital scope. And it was enough for stuff under 100kHz. I couldn't see al transients, butif there was ringing the scope showed the high noise. Since it worked from a 9V adapter (Class II, no safety ground connection), I could stick it anywhere. There was only one time i had to change the protecting diodes at the input, and it was from a tube amp, not SMPS.

I only have a x10x probe, and it was cleary enough (with it the maximum voltage input is 1000V). Now i have an EMG 2x60Mhz analoge oscilloscope to. For measureing both sides, determining ringing it's very good.

For beginners: always keep your desk clean! Safety is the most important. I also reccomend every one buy an RCD (Residual Current Device = RCD, Fehlerstromschutzschalter; it measures the current difference between Neutral and Line, and if tis over a treshold it disconnect Mains), it safed me from lots of electrocut.

 

[TO-247]

Since there will be some DIY SMPS projects in here, or may be at any other locations.

I wrote the below paper for the DIY people, In order to help them making there own SMPS, while following some safety procedures.

The paper talks about Necessary Equipments needed for SMPS development, and some warnings you should be aware of.

Other papers will be launched soon.

Thanks MicrosiM for that pdf.

What you thinks about RIGOL DS1102E :

100MHz-1GS/s

http://www.rigol.com/prodserv/20/

 

[MicrosiM]

this Scope will do the JOB, with Isolation transformer and x100 Probe!

 

[TO-247]

can you explain about isolation transformer ?

 

[TO-247]

Unlike many power transformers, isolation transformers have a 1:1 voltage ratio. The output voltage is (for practical purposes) identical to the input voltage. They serve only to "isolate" the device from the high-current potential of the mains. DON'T use an auto-transformer--they don't isolate.

Transformers also have a Volt-Ampere or VA rating . VA is roughly analogous to wattage (remember, wattage = voltage * amperage, or wattage = V * A.) for resistive circuits , but not for inductive loads. For inductive load, you can "guesstimate" wattage capacity = VA * 0.7, or the wattage of an inductive load is ~70% of the VA.

http://www.instructables.com/id/Isolation-transformer-upgrade-for-old-guitar-amps/step6/Choosing-an-isolation-transformer/

 

[MicrosiM]

can you explain about isolation transformer ?

Isolation transformer, is used to isolate your equipments from the 220VAC line, or 110VAC line. to prevent serious problems when testing or developing SMPS.

In real life, isolation transformer will take 220VAC or 110VAC and give you same voltage as input.
Without connecting your oscilloscope to the 220VAC line.

In that case you will isolate your oscilloscope from the 22VAC line.

 

[zabi]

if you do not possess Isolation transformer and you need to use scope, your analogue oscilloscope should not be connected with ground. That means the ground wire of your scope should be disconnected from mains supply. Use of scope with ground wire connected will surely damage your scope.Warning this way is only for experienced men and it may result in personal injury as well.

 

[tebci]

I have 60-0-60 transformer from audio amplifier, can I use it as isolation transformer for my oscilloscope?

 

[zabi]

I have 60-0-60 transformer from audio amplifier, can I use it as isolation transformer for my oscilloscope?

Isolation transformers are used to provide galvanic separation from incoming supply voltage.It means you need a transformer having two equal separate windings . if your oscilloscope operates on 220v then you need 220-0 and 220-0 on both primary and secondary side.
About the transformer you are asking,it is not clear what is rating of other side winding. 60-0-60 means one side winding having one point common in middle of that winding.you can get 120 if you use the outer terminals.but voltage of the other winding is not mentioned.Beside this current rating of the transformer should be sufficient to meet the oscilloscope requirement.