fan current

I think the Sunon PF40561BX-000U-S99 might have been one that worked this way. I'll check this when I get to work tomorrow.

They're in stock at Digikey, BTW.

Regards, Allan

sensors.

fan

cycle.

I think I used a 10uH inductor the last time I did that (in 2009). It worked fine.

Like Lasse, I used a standard switcher and adjusted the voltage by feeding current into the divider that set the voltage.

These days I use four wire fans in new designs. (The four wires are: 0V, 12V, Tach, PWM.)

Regards, Allan

I just made up some numbers for the demo. I don't recall if there was actually a significant power hit. But, yes, this was 30+ years ago and it was 50% TTL and 50% analog pin driver chips (my design ;-) ...Jim Thompson

That removes everything from the screen except the graticule and waveforms... no text at all, like an old analog scope. "Menu off" leaves a little summary at the bottom.

I don't think I'll ever use an analog scope again. They seem barbaric now.

The low-end Rigols are nice scopes, good performance and easy to drive.

This Tek is buggy.

You mean the $350 models?

Yes. Amazon has a 100 MHz dual-channel Rigol for $359. It's a very nice scope.

We have the 1 GHz Rigol, which is really impressive. It cost a few K less than an Agilent equivalent.

We're about to measure its channel-to-channel jitter performance; I expect it will be a few picoseconds RMS. The c-c jitter of a 100 MHz Rigol is around 30 ps. That turns out to be interesting.

As far as storage scopes go, I do have a couple of digital models which I don't really bond with and avoid using if at all possible. Nothing beats my old Tek 466 and I wouldn't swap it for anything. You need to get rid of that heap of Chinese junk, chuck it in the nearest dumpster, and get yourself a 466 before they become unobtainable.

Analog storage scopes were terrible. Writing rate was pitiful, except for the microchannel things that had limited tube life. The storage interface is clumsy.

The Rigols are great. Color, cursors, frequency counter, FFT, screen capture, measurements, computer interface, at a small fraction of the cost and weight of a tube scope. They are great in automated test sets.

I must have 20 tube scopes downstairs in my collection, but I never use them. We do have a bunch of 50 GHz 11801 types, but the only tube there is the raster-scan (magnetically deflected!) display. It's all digital otherwise.

Yup. I have a Tek 475A and a 2467 (350 MHz, MCP CRT). I rarely use them--what I usually rely on is the TDS784A and TDS 694C for general purpose use and the 11802 or 11801C for super fast stuff.

I also have one of those $400 Owon things with the big screen, which is fine if you don't expect too much.

Cheers

Phil Hobbs

A motherboard I bought recently runs a calibration routine where it ramps the PWM of all the connected fans up and down to find the point where each won't start and uses that to determine the output span for the (optionally) closed-loop control.

--sp

I was just looking at some of their new ones, huge touch screen so you can pinch and stretch to see waveforms up close, either in run or stop mode. Didn't ask the prices, but they look pretty decent. Nice quality Tek-type feel to the handle and quite thin. Unfortunately they didn't bother making a snap on cover to protect the display, which would have been nice.

--sp

I visited a drone company, and their only scope was a Rigol with the LCD smashed. I wonder how that happened.

Drone-related injuries must be up a lot.

Last week I saw a large quadcopter that could hover a few inches above the floor dead stable. I think they're fusing ultrasonic ranging data with the IMU and GPS data.

The small ones are tiny- maybe suitable for causing eye injuries or delivering a dose of polonium.

And you can watch competitive drone races-- not related to watching submarine races. Maybe drones will be the killer app that boosts VR/AR/MR out of the gamer silo.

--sp

We have to move our company, so we are looking around at industrial spaces. The droners are in an old warehouse that had been mightily pimped out: sandblasted old wood structure, shiny hardwood floors, fancy stairways and glass cubes hanging in space everywhere. The asking lease prices are insane, which is maybe why the droners are moving out. They ran out of cash a year or so ago, so raised tens of millions by pre-selling tens of thousands of drones... and haven't delivered any. Should be interesting.

Yes, drones could cause all sorts of accidental and intentional badness. A little imagination suggests all sorts of stuff.

Or it could just be ground effect: that should be possible open-loop.

Here is one I measured recently in "steady state":

RMS current can be 60-70% higher during spin up. The fan supply could deal with the steady state current, but not spin-up. Thus it hiccupped. That is why I was looking at the current.

Sorry to hear you have to leave that building you so carefully rebuilt.

These current waveforms are used by some fan controllers to measure the rotation speed and sense faults, Microchip TC642, TC647.

Hi Win,

This fan has a tach output (open collector) and also a PWM input to control fan speed. Neither is connected for the given plot, as they are optional. This means the fan is running at maximum speed.

Greg