Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by tggzzz on Today at 02:36:37 pm »

What could be a proved single opamp for a wien oscillator?

Anything with sufficient frequency response, and output voltage swing, and drive capability.

Since you still haven't bothered to tell us those parameters, how do you expect us to help you?

In addition, ponder the second paragraph here.

More thread-choking negativity and useless crap from tggzzz. 
He's a real thread-killer if I ever saw one!

Your question about op amps?  I use T.I. OP07's with excellent results in my low frequency sine wave oscillators.
Data Sheet link: https://www.ti.com/lit/ds/symlink/op07c.pdf?ts=1714331934514&ref_url=https%253A%252F%252Fwww.google.com%252F

Also, check out the numerous TI App Notes for oscillator designs with sample circuitry you might use as starting points. Best Regards.

The context is these threads from MajorAssBurn:
https://www.eevblog.com/forum/buysellwanted/fs-affordable-dmm-checkers-ac-reference-dc-reference-ohms-reference-etc/msg5463700/#msg5463700
https://www.eevblog.com/forum/metrology/affordable-useful-ac-dc-references/msg5438690/#msg5438690
Anybody with too much time on their hands can read those. They will, no doubt, notice that many people have made negative comments about MajorAssBurn's claims in those threads.

BTW, it isn't good practice to read the first couple of posts in a thread and then jump to conclusions without reading the rest of the thread.

I have this mental image of tggzzz sitting in his week-old undies and moth-eaten robe, in the corner of his tiny, gloomy, cold-water flat, in a poverty-stricken slum section of Birmingham, pecking away at his twenty-year-old Pentium computer while desperately searching forums and threads for topics wherein he can spew out his unwelcome drivel and negativity and display his legendary (in his own mind) philosophical and technical superiority as compared to the woefully ignorant and uninformed commoners who participate in these threads looking for useful suggestions from fellow members, as he, the self-ordained master of thread imposition, reflects within himself how utterly failed as a human being he is, as he seeks out these thread-killing opportunities so as to feel somewhat compensated for his lifelong worthlessness and complete failure to achieve anything noteworthy or meaningful.

Now, with those facts in mind, I will ignore all further written diarrhea that tggzzz dumps in various discussions from now on. 

That's an excellent response focussed on the technical aspects of the threads. Good to see you've avoided ad-hominem attacks.

Hint: to ignore me, simply add my moniker to your Profile->Modify Profile->Buddies/Ignore list.

2

Beginners / Re: LiPo battery charging problem

« Last post by hap2001 on Today at 02:35:15 pm »

Thank you everyone!

3

Test Equipment / Re: Standardised Way To Test Oscilloscope Screen Update Rate

« Last post by XiMMiX on Today at 02:32:43 pm »

That sounds like using the screen's refresh rate which may not be the actual update rate of the information on the screen.
As a comparison, the screen I'm using on my computer runs at 120HZ but if I'm watching a fullscreen jpg the actual screen update rate is 0.

4

Projects, Designs, and Technical Stuff / Re: Control of 2 CAN Open DS402 motors on a single shaft

« Last post by Simon on Today at 02:30:57 pm »

Ok, i'm gonna ask another "stupid" question: Does the system actually NEED two seperate motors?  It's going to be cheaper, simpler, and more robust to just fit one motor to do the work if you can!

Ie, rather than have to invent some complex control archecture to suit some dynamic load you may never get a chance to properly validate, just simplify the system to one drive node!!

hahahahahahahahaha, you know me, if I could have, I would have. Various factors drove the 2 motor solution. It was mechanically simpler (yes I still have that problem where the electronics fixes the mechanics problem but I get some thanks now) and we struggled to get powerful enough motors, both single and dual have been used in the past, with hydraulic motors they are plumbed in series and yes I considered that electrically as well.

The drives have many settings and bits of information available. and looking around the internet I have seen some examples of how these sorts of drives are used to construct complicated machinery with the control being offloaded to the motor drives. For example conveyor belts is where I first heard of this speed control one motor and have one or more torque controlled helper motors. Our application is similar. another was a paper mill with one roll being unwound onto another with a motor winding and another holding back the unwinding roll with a torque that it calculates from the output of a pressure sensor on the paper connected directly to it rather than through a main controller.

So I realized that I have been missing a trick with these motors worrying about if my little 48MHz M0+ micro can keep up with all of the messages on the bus that I need to do really fast control, I should simply let the motors work for me and just send the sync message as fast as I like as I don't have to process much data coming back. The motor drivers have a 120MHz ARM M4 each.

At first I wondered why on earth I would want to know the motors target_torque, all I care about is that I sent it a torque_demand  and that it gives me what was demanded of it, if anything I would only use the actual_torque value to see what is happening. Now that I start to see how these drives can be used it makes sense.

If I can have the speed controlled motor change speed at a rate of 0-max in 5s that is well slow enough I think for a motor that is taking the target_torque of that motor to keep up would be easy enough. With sync messages sent every few ms long before the speed controlled motor has finished making an adjustment if it is transmitting it's target_torque the helper motor matches that. This should mean the speed motor now sees less load so adjusts to suit. I don't know how far into the future the tarqet_torque is but after a few cycles I would expect the two motors to work together quite well as the speed motor quickly gets used to the reduced load. It would really be about that first cycle where the torque motor has to come in and the speed motor gets a bit of a surprise. once both have a similar torque value I would hope that the speed motor would start to see half the load as the required change in load would be quit slow.

5

Projects, Designs, and Technical Stuff / Re: Build or buy? Multi-level vessel temperature logger

« Last post by mag_therm on Today at 02:28:38 pm »

https://www.watlow.com/products/Sensors/Thermocouples/Multipoint-Thermocouples

6

Beginners / Mobile Stepper Motor Driver Project / Use of membrane buttons

« Last post by Jasonkandefer on Today at 02:28:16 pm »

Hey! New here, I’ve been a lurker for a while and decided to make an account and ask a few questions.
About a year and a half ago, I came up with an idea for a tool that I could use at work (commercial HVAC technician) to be able to calibrate and diagnose issues with Electronic Expanion Valves. These “EEVs” use a stepper motor to open or close valves to meter refrigerant. I’ve dabbled with Arduino and breadboards before this, and was finally able to come up with a working prototype that used numerous premade pcbs (boost/buck converters, Arduino nano boards w/ breakout pcb, external battery life indicators etc) obviously having this many separate boards all being manually wired together was not a good option as it was fragile and buck/boost converters were melting if I hooked up to an EEV that drew a tad to much power. I dabbled with having guys on fiver make me some actual PCB prototypes, but after spending 5-700$ on having boards ordered an assembled through JLPCB, I still didn’t have a working prototype, which leads me to the old saying “if you want something done right do it yourself” so I downloaded kicad, started watching youtube videos, and began prototyping simple PCBs until I started getting the hang of it. Well, 7 months after downloading kicad I have a pretty complex PCB using an ATMEGA328P-AU & an A4988 stepper driver IC. The atmega chip produces a contact 330Hz square wave for the a4988, and also controls the button logic for enable/direction & speed controls MS1,2 & 3. The board is powered from a 3S AAA 3.7v battery pack delivering 12.4VDC to the PCB, an ATTINY and a low quiescent linear regulator is used for turning the device on an off, the ATTINY stays in sleep mode until the button connected to one of its pins is pressed and held for 1 Second, it then wakes up, and outputs 5v to the gate pin on a SOT223 2N2222 Transistor that makes contact between battery ground, and the ground plane on the PCB, enabling 12VDC to the rest of the board. Another 1 second press will then shut the board off.

My real question here is since I also dabble in Cad, (solidworks & shapr3d) I’ve designed a case for this project, but I want it to be sleek, and durable. So I’d like to implement the use of a custom membrane switch keypad. I’ve looked at some websites and seen I can have them prototyped for around 300 USD. Has anyone had a custom membrane keypad made? I have & can use photoshop to design the button graphics, and can design the schematics for the buttons aswell, would this cut down cost? What is the process of having these keypads made? Any suggestions for an easy to work with company for making these?

Thanks. 

7

Beginners / Any off-the-shelf clock using DS3231?

« Last post by hap2001 on Today at 02:28:03 pm »

Hi.
I'm looking for a very accurate home clock, and many search results point to DIY projects using DS3231, they say it's the most accurate chip you can get without cost a leg.
I just want to know, is there any commercially available clock that have DS3231 as it's gut, or something else with equal or even greater accuracy?
I know a Wifi connected clock would be always accurate, but I just want a stand alone time source.
Thanks.

8

General Technical Chat / Re: piano switch

« Last post by reboots on Today at 02:27:28 pm »

This is an on-off switch, identical in function to a top-actuated DIP switch. The datasheet doesn't explicitly state that, but the listed typical applications are a clue: "Address switch for industrial controls" and "Logic switching for computers and peripherals" would not ordinarily use a momentary switch.

Datasheets will call out "momentary" or "MOM" for a momentary switch. Another convention is to use parentheses to denote a momentary function. For example OFF-ON and OFF-(ON) would indicate two switch variants, with the latter being momentary.

I have never seen a momentary switch of this type. The best I can suggest is a tactile pushbutton switch.

9

Projects, Designs, and Technical Stuff / Re: Opamps - Die pictures

« Last post by magic on Today at 02:27:00 pm »

Would it be ok for you if I put your schematic on my website?

OK

By the way, I forgot to mention that there is one error here which I am not going to correct because I'm too lazy to use the full, four-terminal MOSFET symbol.
In integrated CMOS technology the bodies are often tied to one of the supply rails, not necessarily to the source, and this appears to be the case here.

I noticed that IC designers often use simplified symbols similar to NPN/PNP which don't even show the body at all, unless they are doing something unusual with the body of one particular transistor. Maybe I should add these symbols to my LTspcie...

10

Projects, Designs, and Technical Stuff / Re: No interrupt from AS6501...

« Last post by Denge on Today at 02:26:06 pm »

Hi All,

Porting this code to the dsPIC33CK64MC105 MCU would take me ages I guess. On top of that I'm a novice in programming C.... So trying to port all this code would bring me further away than I'm now!
By now I checked and rechecked the hardware and found it should be ok, played with some different setups and added a 100 µs delay right after the power on reset and a 200 µs delay after the configuration write but still no interrupt going low! :-(
The config I use now is:
cfg0: 0x95, cfg1: #0x15, cfg2: #0x00, cfg3:4:5, 100000, cfg16, #0x04
The refclk is 10 MHz.
Conclusion: I'm lost

Greetings,