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1
Aha, thank you both! The additional current is specified for inputs at Vcc-0.6V, but I assume that it applies for any input voltage which is not (pretty) exactly Vcc or 0V? Is it essentially getting worse the farther the input is away from Vcc or 0V?

some datasheets have graphs like: fig8/9,  https://assets.nexperia.com/documents/data-sheet/74HC_HCT14.pdf
2
There are extruded enclosures that have grooves in the sides so that a board can be slid into the slot.  Then, there are end plates that can be machined with connector cutouts, and these are screwed to the open ends of the extrusion.  I used these for a project I did.  The one issue was I was machining the end plates which were anodized, and the hard anodizing destroyed my solid carbide end mills so fast that I could only make one plate per end mill!  The plan for future production was to make the connector-side plate out of unanodized aluminum sheet and then apply a label that matched the color.  These enclosures are plentiful and surprisingly cheap.  I think I got mine from Newark for about $12 each.
Jon
3
I found a Chinese company selling matching ferrite beads on eBay and the part number started with BIT.
Thanks!
4
never mind
the pinout does not match the prescaler chip. input and output pins are visibly at very different locations

so NB7N017M can not replace the Agilent 1822-1124 prescaler. it's not the same chip.
it is probably a variation of that chip by onsemi made for agilent.
5
Repair / Problem with air compressor pump motor
« Last post by shockpoint on Today at 02:54:28 pm »
Hi all.

I have a compressor motor head exactly like the one in this video.
In this video, the construction of the windings shows that the run winding has both in and out terminals as RED. and the start winding has both in and out terminals as BLACK.
Based on my multimeter check, on my own unit, the black wires do NOT have continuity with one another and neither do the red. The only continuity is between one black-red and another black-red. So I believe on my unit the color is arranged differently.
So please note that in my below diagrams, the black and red refer to what I believe to be the arrangement of the winding terminals on my particular unit.
It is a 580W, 230V AC pump that is most likely a permanent start capacitor motor. The nominal current on this is 3.8A.
The capacitor is 25uF rated for 450V and I bought it new and verified that it works.

I have an issue with mine that I cannot figure out.
I have tried wiring my motor in two ways.
The first way I tried is to wire it in the way suggested in the video above, which is summarised in the line diagram as shown below (first picture attached). Note again that in the schematic, the black and red denote what I believe to be the in and out terminals for each winding, and not differentiating the start winding and the run winding as in the video.

Key:
L = line, N = neutral. There is a ground wire, and it is connected to AC GND.

This method resulted in:
- the circuit breaker tripping
- There was no audible hum in the motor

The second way I wired it is according to the technician at the store (my compressor is out of warranty and I want to know what is the problem with this motor so for those reasons I would prefer not to take it into the store as they are unlikely to offer more help), who told me that:
- the two red wires, contrary to the video above, were actually meant to be directly connected to the capacitor, while the two black ends are meant to be connected to L and N (with a green for GND of course).
- this also resulted in a circuit breaker trip.
- this arrangement does not make any sense on a line diagram. See the second photo, which is essentially what I think the technician is telling me. Although on the shop units I have seen this to be the case. Here is a photo of the shop unit. https://ansaleeov.xyz/product_details/38663846.html (see photo 3 for annotated picture)
As you can see, coming from the side of the compressor through a bunged hole, are two black sheathed cables. the thin one threaded under the compressor unit goes to the capacitor (this sheath contains the two red wires). The thicker sheath going to the pressure switch  contain the two black wires and a green-yellow ground wire.

My areas of confusion:
- I have measured the black and red wires on a multimeter. On black-red pair 1, I am getting 13 Ohms. On the other black-red pair 2, I am getting 1-2 ohms. Are these expected values for the main and auxiliary windings? Based on the video above the construction selects 21AWG for the main winding and 23AWG for the auxiliary winding each with different winding dimensions, so I have reason to believe that this possibly could affect the reading but I am not sure if a 12 ohm difference is reasonable. Assuming a current of 3.8A, 13ohm*(3.8A)^2 (power) results in a heat dissipation in watts of 187.7watts. This seems a bit high to me. The alternative winding, 2ohm*(3.8A)^2 = 15.2 watts seems more reasonable.
- Between the black and black wires, there is no continuity. This would suggest that black-red pairs are end terminals of each of the windings in the motor (main and auxiliary).
- However, if the capacitor was meant to be connected directly to the red pair of wires, and the L/N wires straight to the black terminals, then this means that the wiring diagram would look like this (second photo). This line diagram does not make sense to me as a PSC motor and I cannot see how the capacitor could possibly generate a phase shift to kick start the motor.

I have no idea which way is the right way to wire it.
And I also have no idea what to think about the motor windings themselves - are they actually bad? I thought the windings should be relatively similar in terms of resistance.

Please help! any ideas pointing me in the right direction would be much appreciated
6
The VDD33USB pin supplies the USB internal transceiver. (On smaller packages its connected to VDD)

The VDD50USB pin is available on the larger packages as a 3.3V regulator input.
However, the regulator is disabled by default. The chip boots up in bypass mode (VDD33USB = power input), and you can enable the regulator to then supply that pin from VDD50USB.
That means that powering the STM32 won't work as the regulator won't get enabled.

I think the only selling point for having this regulator, is so you can power the MCU at VDD=1.8V and have USB operate in its own power domain of 3.3V. There are no specifications on this regulator, so its anyone's guess if it can deliver say 100mA for the STM32 part itself.

See 6.4.7 of the reference manual
(and perhaps AN5419)
7
I am  working on a separate "hardware" watchdog timer to stop ham sdr radio transmitter in event of cpu hang.
The timer I selected is "DC 12V FRM01 Timer" one of the generic modules available on Amazon, $17 for (2).

It has 18 modes, 0.1 s to 270 h  and  a 14 page programming manual that can be downloaded separately.
 The c/o contact is rated 125V AC 10 Amp, but recommended rating is 1/2 for resistive  or 1/3 for inductive/capacitive.
The AC contacts look well sized, separate from circuit and surrounded by ground plane
The modes are programmed with onboard buttons and led numeric display. There is a terminal for 1 20 ms pull up/pulse contact.

This timer comes in versions for 5V, 12V  and 24VDC supply, and there are a number of similar ones to this part number.

I am familiar with those  particular timers.   I usually avoid them because it's just the board and then you  have to figure out some sort of enclosure.   When I use off-the-shelf components like that I actually look to the home automation space.  Those devices are super simple to configure as a timer and enable you remote access to the device both to monitor and control.
8
Hi folks. i have the same problem with my acer aspire 8930G,my laptop keeps restarting while booting,even if i boot from a cd.
cause 2 people here said 2 solution,one soft and one hard, i tryed the soft one to boot in safe mode and indeed it booted fine. so cause it booted in safe mode,means it is the nvidia graphics cards faults?and what is the solution to that?also means it is not the tokin chip problem that another user said?
9
A microcontroller is what I currently use as I stated in the opening post.  An Arduino would work as well.   I was just looking to expand my knowledge and see if anything could be improved upon or be made aware of something I was not.  Thank you.
You can use the smallest, simplest, 6-pin  microcontroller you can find and program it in assembly, rather than C.

That is a great suggestion.  I can code in C not assembly.   Thank you.
10
Thermal Imaging / Re: Uni-t UTi260B
« Last post by Algoma on Today at 02:38:24 pm »
Mine lost half its calibration settings (Corrupted flash memory? set the values to zero). While I was able to roughly recalibrate it back to within "Goood enough for what I need" though trial and error while setting various calibration points, its still nowhere near factory, Thankfully I'm only looking for unusual hotspots on system boards.

Its always Best to avoid adjsting any existing calibrations, Though you now have video backup of the current calibration values. It looks like its more software related in this case. There is a factory reset option in the user menus, Be familar with the menus first, as it will reboot in Chinese language as the factory default setting.

Your calibration menu v2.0.22 is also improved, with -10, 20, 100 Calibration points.  Mine only has 10'C and 120'C points with an older v1.2.10 firmware

3 points can make a calibration curve, while two only makes a line of (Offset + Slope).
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