really nice Rigol scope

Or maybe he could invest $5 in a mouse with a scroll wheel. No, he'd rather whine.

scopes.

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Sure, capacitors can be a bitch. ;-) However, there are limits on how slowly you can bring supplies (and loads) up, as well. For big supplies, this can be tricky.

Digital spectrum analyzers also exist. Most high-end ones are some sort of hybrid nowadays, with a downconverter feeding an FFT analyzer. Making a tracking generator for a FFT spectrum analyzer is sort of hard. ;)

Cheers

Phil Hobbs

cuz yer easy

delay.

Hmmm. Pretty nice. DSA815 without TG $1295 and with TG $1495. DSA1030 without TG $3999 and with TG $4999.

I am afraid that they are all currently out of my reach.

?-)

scopes.

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Not the capacitors so much as the negative input impedance at the input of a switcher. You've got to let the main supply, wall-wart or whatever, pull up before you let the switchers loose, or the main supply may current limit and bog down.

I just did my first USB box, which can either do a full USB interface, or just get power from one of those USB-type charger warts, with control from trimpots. It turns out to need the full 500 mA. A "1 amp" cheap (like, $1) USB wart won't work; the $4, 700 mA rated Samsung works fine.

The micro-A/B connector is upper left.

Good points. What's really annoying is that most "electronic" car battery chargers, the ones they sell at auto parts stores, will not put current into a fully discharged battery. I think it's a scheme to sell more batteries... "If it won't charge, it's dead, you need a new battery."

Last time that happened to me, I had to hack my own charger out of stuff found in the garage; an old DSL transformer-rectifier power supply and a belt sander as a current limiting resistor. I keep a power supply around now.

The new Tek MDOs feed the DPO's captured waveform into a hardware FFT analyzer to get the "real time" frequency domain information. The two can then be displayed in time sync. It's kinda slick.

Uh, yeah. Maybe an RFFT into... Hmm. Well, that's how sorta Agilent does their arb generator. ;-)

Be careful with USB warts. I'm looking for 2A USB wall warts but so far no luck. Even when specified for 2A none actually deliver anything over 1A.

Isn't 2A a lot to push through USB cables and connectors? I think the spec is 500 mA.

I often look for these sorts of things, and come up with little.

Depending on what bandwidth you need, it's probably easy enough to just build a beefy class-B emitter follower stage inside a unity gain buffer stage, referenced by whatever signal source you want, be it a DC value or some signal gen. Of course, that lacks a current limit.

There are a few nice several DC to several MHz power amps on the market, for boosting signal generators, exciting piezos and small servo motors, etc. But at 10A, hmm...

I have a 72V 7A DC-10kHz class-D servo amp based on an Apex chip that I built and designed at work with some help here a few years back. It can do about 15Apk, but not 10A continuous. But it has a current minor loop inside a voltage loop, and a whole bunch of configuration options, so it can do a lot of tricks.

The point of my sharing the experience of getting two features added to the Agilent scopes is that they were willing to listen and work with a customer to enhance their product.

This could be an important value added, that might be difficult for a Chinese manufacturer to provide.

It doesn't seem like what you need to see in the new counter is almost the same thing as I wanted from the scope. Though, they may need to omit the pre-averaging (I'm not 100% sure what you mean).

I would be happy to call Jeffrey Cuyle on Tuesday morning, who was associated with the 7000 series scopes, and who helped me get in contact with the manager in charge of the 3000X development team, which eventually led to my being able to have direct contact with a 3000X programmer--to try to get you a contact who may be able to initiate a process of improving/enhancing the stats capability of that new counter.

The new 3352xA function gens. came out with hideous glitches in their outputs, when UI input occurred. Caused me to blow up a few LEDs and MOSFET drivers before I documented the behavior and sent it to them. They got it improved a bit within a couple months when the next firmware came out. I still need to go back and document the slight problem that remains.

It does seem like they are rushing some of the new instruments out the door once the hardware is off the line, though the firmware is just not adequately vetted. But they are also responsive to the customer when bugs are reported, and features are requested.

Let's see if they can fix up that counter for you!

Perhaps some of the reason why they have been so nice to me is that I always preface my conversations with "so I have some great ideas to make your products beat the pants off Tek..."

And I couldn't get a high end Tek DPO7000 series, or Agilent 9000 series to do it when they demoed them.

LeCroy loaned me a 1GHz 4-ch thingy for 2 whole weeks, and I had it set up to do the calculation, with the trend plots in about 2 hours after never seeing one before. People whine about the LeCroy UI. Maybe older models were odd (though I recall we had one in the physics lab at college in '97 that was easy as pie to figure out). I don't have any problem with the UI.

So I bought the LeCroy. Then Agilent added the rel. std. dev. a few months later. But still, the LeCroy is better since the mid-range Agilent scopes that I can afford still can't trend plot the measures.

I just wish I could complete a home project in less than 3 years.

I finally got some Russian VFD tube pins straightened today to plug into my new clock PCB. Took me 2 years to complete the PCB design. Just have to order a few more parts and hardware...

scopes.

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;-)

one.

soon.

impedance

You aren't worried about the rotational life of the trimpots on the front panel? They're usually horrible--100 cycles or less, vs. 50k to

Cheers

Phil Hobbs

Really? Blech, 7-8 ENOB for a spectrum analyzer.

You could always try using a delta function, I suppose!

Cheers

Phil Hobbs

Kepco BOPs. I recently bought a +-50V, +-2A one for a couple of hundred bucks, and they come much bigger than that, e.g. the BOP 20-20M, which is +-20V, +-20A.

Cheers

Phil Hobbs

scopes.

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be asking

;-)

decoding.

(Measure|Statistics):

one.

soon.

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to a

slowly

be

We.ve used these before, lots of places, and I'm not aware of any problems. They are cermets, about the same construction of panel pots.

thinking

I brought that up in the demo. It's probably not useful as the only SA, but being able to look at a signal in the time domain and frequency domain simultaneously would come in handy for EMI work. OTOH, $28K (full blown) is kinda hard to swallow for a bench tool.

We had a USB plug grafted onto a standard 2A WW, for a battery charger. The tooling for the mold wasn't outrageously expensive,even for a run rate in the thousands per year.

Mini-Bs come in 1A and if you look hard, 1.5A varieties. 2A will be standard for Micro-Bs soon. Apple is demanding it and everyone is following. Mini-Bs will likely go out of favor very soon.