Recent Posts

1

Test Equipment / Re: Siglent SDS2000X Plus - Bugs / Missing Features / Feature Requests

« Last post by BillyO on Today at 05:01:33 am »

Interesting proposal though, I wonder if the HW supports backlight OFF.

It is under UI control, so that does imply the HW is subject to the SW.  This should be possible.

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Test Equipment / Re: Siglent SDS2000X Plus - Bugs / Missing Features / Feature Requests

« Last post by tautech on Today at 04:57:38 am »

I'm into the habit of winding back brightness to 80%.......for no good reason other than not needing full brightness.

Do you have any idea about my question: Is there a reason the screensaver doesn't shut off the backlight?

Zip/zero.
Interesting proposal though, I wonder if the HW supports backlight OFF.

3

Test Equipment / Re: Siglent SSA 3021X... Ooops

« Last post by tautech on Today at 04:55:28 am »

Its already in pieces. I was doing some tx measurements and left my attenuator out when making a change. The SA got 6 Watts pumped into it. It is not working properly now, levels are wrong, frequency is also off a little, I worry that might be a bigger issue. Measurements were fine until my screwup.

Shame. 

Really we need screenshots to advise.
Normally damage to the front end results in 20dB error however I have one here that won't show any RF In levels. 

Here's one of a few mistake/damage threads:
https://www.eevblog.com/forum/testgear/what-happens-when-you-blow-the-input-of-a-6500-siglent-ssa-3075x-plus!/

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Repair / Re: Mig welder wire feeder controller board not working

« Last post by TERRA Operative on Today at 04:53:57 am »

Here's the Service manual for the feeder and other documentation I could find.
(Linked here in my Google drive too, the welder service manual is too big to upload here)
If you let me know the 6 digit model number of your welder, I can check if I have the exact manuals. I assume it is probably 706118?

I see the schematics for the wirefeeder, including board level components etc are in the service manual which is nice.

Page 17 has the voltages, and from page 18 has a troubleshooting guide that should help narrow down the problem a bit.

I would first disconnect the feed motor from the control board in the feeder and briefly apply voltage (24V) to ensure it is not jammed or seized, and give the motor a sharp tap with the handle of a screwdriver to loosen it up if something is stuck. Also check the brushes aren't worn or stuck.

As an aside, make sure your rollers are free to turn (grease the shafts they spin on), and the gears aren't worn as they can start to jam if the teeth are badly worn. Also make sure the wire path and grooves in the rollers are kept perfectly clean for best grip on the wire.
Poking the wire through a foam earplug before it enters the feeder assembly is a cheap trick to keep the wire clean as it goes through the rollers.

5

Beginners / Re: Jutter calculation ?

« Last post by bdunham7 on Today at 04:52:46 am »

When you generate a square wave or pulse with DDS signal generators at anything but a submultiple of the DDS clock, you'll get varying rise times but the AWG will typically try to minimize the jitter as measured at the zero crossing or the midpoint of the waveform if it isn't symmetrical around zero.  IOW, that really isn't jitter, at least not it the way that it is typically defined.

6

Beginners / Re: Automatic golf ball dispenser

« Last post by Maclarkson on Today at 04:49:44 am »

Ok so moving on to the problem. I managed to get something working. I connected up a sound sensor module the Arduino, power, and a relay module. What’s the best way to connect the solenoid to the same battery via the other side of the relay. See pictures. Problem is the solenoid obviously drains too mush current. Because the leds on the Arduino take a dive. How should I best connect up the solenoid?

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Projects, Designs, and Technical Stuff / Re: 3D printing company similar to PCBWAY for circuit board

« Last post by sw_guy on Today at 04:46:44 am »

www.shapeways.com

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Programming / Re: Angle wrapping in code, "easy" problem, need to double check

« Last post by golden_labels on Today at 04:44:43 am »

To avoid branching with 16-bit integer inputs, you may shift the input so the lowest input value congruent to 0 is actually 0, and % that:

Code: [Select]

int16_t truncate360(int_fast32_t value) {
    constexpr int_fast32_t lowestZero = INT32_C(360) * 91;
    return (value + lowestZero) % 360;
}If you want to cover the very end at the bottom (below 32760), just shift it by another 360 (that is: 92 steps, not 91).

The above isn’t going to work nicely with arbitrary floats, because it relies on calculations being done in a type with a range at least twice the input. And even if the value fits, it may lose a bit of precision.

As for the “true” value: in both C or C++ word “modulo” is never used in reference to the % operator. The behavior of / and % is defined by this single identity: (a/b)*b + a%b == a. So the language isn’t even making a claim of supporting such operation. But, if it did, “mathematical” modular arithmetic is not inherently positive either. Some languages simply choose to use positive remainders, but it’s an arbitrary choice, not truth. It may be useful to limit operations to integers ring modulo N, but it’s not truth.

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Test Equipment / Re: Siglent SSA 3021X... Ooops

« Last post by Joel_l on Today at 04:40:40 am »

Looking at it more, I believe the parts 956P are switches. Looking at the path, it looks like the first switch switches in the 49R9 resistor, going farther down the path it looks like the other switches control some attenuators. Not sure why the 50 Ohm termination would ever be switched out.

10

Repair / Re: Mig welder wire feeder controller board not working

« Last post by coppercone2 on Today at 04:40:18 am »

i wonder if they have a hand crank fed mig some where

the deep future of welding is a hand cranked super conductive dynamo that both feeds wire and generates electricity to power the welding process, for body repair in the far corners of the galaxy (New Pakistan, 12,101 A.D)