Recent Posts

1

Beginners / Re: Automatic golf ball dispenser

« Last post by ledtester on Today at 04:13:28 am »

Ok guys, the final prototype.
https://youtube.com/shorts/KOmL9WKCEq0?si=T7d2N874ycgET7hB
It would have been nice in their forum if someone could have suggested ways to achieve this.

Here's how it seems to work... the plunger of the solenoid above the ball exit keeps balls inside the bucket. When the solenoid is activated the plunger moves upwards letting a ball roll onto the ramp. The solenoid is timed to only let one ball onto the ramp at a time.

The components are just two battery packs, a relay module and an Arduino and perhaps some sort of sensor (optical?) on the lid. I think the sensor on the lid is just used to tigger the solenoid.

2

Power/Renewable Energy/EV's / Re: 5 out of 6 vendors are scamming people with wrong crosssection of cables

« Last post by Siwastaja on Today at 04:11:12 am »

Have you ever checked on the cross section?

Another interesting question would be, how did you measure it? I ask because measuring cross section of a multi-stranded wire is not trivial at all. Which is also why, to answer your question: I have never checked. I think the risk of me measuring incorrectly would be larger than the manufacturer lying.

One thing to consider is also tolerances. In engineering, everything comes with a tolerance. Manufacturer's job is to guarantee their product is within tolerances. If they can improve the manufacturing process, they can save costs by making undersized product which is still within tolerances, and no one would be lying.

3

Projects, Designs, and Technical Stuff / Re: more modern version of tl494?

« Last post by xavier60 on Today at 03:54:54 am »

I have a strong preference for the UC3525.
It is reassuring to see in the internal block diagram, the steering flip-flop being clocked directly by the oscillator and also the latch at the comparator's output.
Not so for the TL598 despite the claims. The extra opamp might seem useful but can be difficult to achieve fast current limiting with it.
With the UC3525, I implement fast pulse-by-pulse limiting by pulling down the soft-start pin.

Great info, I have heard a few people saying their problems went away after switching from the TLxxx to the 3525 series, this could explain it.

From the  UC3525 datasheet
All transitions of the voltage on the shutdown pin should be within the time frame of one clock cycle and not
repeated at a frequency higher than 10 clock cycles.

Does this pose a problem to fast current limiting, or do you hold the voltage low for 10 cycles?

Thanks

I only use the soft-start pin 8. It only acts on the comparator input but still terminates the present half cycle quick enough.
A capacitor is normally placed from pin 8  to ground. I include a series resistor so that the pin can be quickly pulled to ground without completely discharging the capacitor with a small transistor or possibly a comparator's open collector output.
The transistor or comparator will be monitoring the rectified, loaded and lightly filtered output of a current transformer sensing primary current.
My application is forward half-bridge converters.
 It provides short term pulse-by-pulse limiting for each half-cycle until a slower main control loop can take control of output current. A battery charger for example.

4

Test Equipment / Re: Siglent SDS2000X Plus Hack

« Last post by rfindley on Today at 03:54:28 am »

I used to write software for option keys and firmware updates, so it's always interesting to see how other companies implement theirs.  I had read that Siglent changed things recently in newer firmware... or maybe just newer models, I'm not sure... so I was curious if this script could reproduce my legit-purchased logic analyzer key for the SDS3000X HD, and nope... it's different.

I was also curious about the .ads files (that's another interesting thread), and it looks like they're still using some of the same obfuscation techniques (reverse file, xor 0xff pattern), but it does look like it's not exactly the same as it used to be.  It's so easy to AES-encrypt these days, especially if the equipment is running Linux, so I wonder why they spend time doing weird obfuscation.  (Maybe it's an export control issue??).  Not that I'm complaining:  some people like Sudoku;  I like my challenges a little more difficult. 

5

Projects, Designs, and Technical Stuff / Re: more modern version of tl494?

« Last post by 2strokeforever on Today at 03:32:44 am »

I have a strong preference for the UC3525.
It is reassuring to see in the internal block diagram, the steering flip-flop being clocked directly by the oscillator and also the latch at the comparator's output.
Not so for the TL598 despite the claims. The extra opamp might seem useful but can be difficult to achieve fast current limiting with it.
With the UC3525, I implement fast pulse-by-pulse limiting by pulling down the soft-start pin.

Great info, I have heard a few people saying their problems went away after switching from the TLxxx to the 3525 series, this could explain it.

From the  UC3525 datasheet
All transitions of the voltage on the shutdown pin should be within the time frame of one clock cycle and not
repeated at a frequency higher than 10 clock cycles.

Does this pose a problem to fast current limiting, or do you hold the voltage low for 10 cycles?

Thanks

6

Beginners / Re: Automatic golf ball dispenser

« Last post by Maclarkson on Today at 03:30:40 am »

Ok guys, the final prototype.
https://youtube.com/shorts/KOmL9WKCEq0?si=T7d2N874ycgET7hB
It would have been nice in their forum if someone could have suggested ways to achieve this.

7

Beginners / Re: 555 driver and Transformer questions

« Last post by Andy Chee on Today at 03:24:24 am »

I have a few thoughts....

Is your current mechanical vibrator system working adequately at the moment?  Can you connect your oscilloscope to the working vibrator to see what kind of duty cycle it generates?

Another possibility is that the working vibrator can be used to drive the gate of the MOSFET (instead of being driven by the 555 timer), the MOSFET (or transistor or SCR) can handle the heavy current switching of the step-up HT transformer module.  This approach would eliminate heat from vibrator contact arcing, but you would still be susceptible to mechanical failure.

8

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

« Last post by .RC. on Today at 03:21:13 am »

Yeah, basic, non critical MIG welding on mild steel is pretty forgiving. I never really understood why some people end up with no penetration on their bird-poop welds....

I actually found it hard to do a bird poo weld with a mig.   What it is easy to do it do a visually fantastic looking weld that has zero fusion to one side.   I have also found cold mig welds on commercially made stuff. The bead stands proud like your nipples on a cold morning.

Mig welders because they are more complex to get the settings right, with volts and wire feed and gas type or gasless or dual shield has opened a whole new level of crap welds.  At least a stick weld looks crap if it is crap and starting out stick welding I did a lot of crap welds.

The old days your 15a socket melting (yes I melted a few of them) AC transformer stick welder had one knob to adjust (well some were flash and had 2 OCV settings), and everyone was running 6013 rods.  Life was simple.

Of course one quirk for Australia that has gone full short bus on regulations.  Dodgy Darryl at his home with his $150 mig welder and a roll of flux core and ten minutes welding experience can weld up a trailer to tow behind his car and get it registered no problems at all.

9

Test Equipment / Re: new killer scope in town - a true game changer from R&S - RTB2002 & RTB2004

« Last post by Darkover on Today at 03:15:04 am »

> RTB2000 is not 12 bit.

Ups, I invented two more bits. 
However, it is noisefree enought that I enjoy it and I think it is very seldom that
I need the gain of 1x probe, especialy if I had to pay with lower bandwith.

Olaf

10

Buy/Sell/Wanted / FS [US to XX] Tek AFG3252 - Like new, single owner - $3K

« Last post by Zucca on Today at 03:03:20 am »

https://www.tek.com/en/datasheet/afg3000-series



I bought it in 2011 spending an insane amount of money.
It was my baby for several years, always a joy to use.
I can't find any defect on it.

It comes with US power cord, two CDs and the cal certificate form 2011.

Lowest I can find on ebay is eBay auction: #305528284623 for $5.5K.
We all know it is pure madness, I will let mine go for $3K + shipping.

Reason for selling: I always use my Agilent 33522A now, I don't need it anymore.

PS: If you have a Agilent 34972A to trade in, I will make you a discount.

Free shipping in US lower states, others please ask.

Datasheet attached here below.