Recent Posts

1

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by john23 on Today at 05:19:07 am »

Hello XVR, You said i should put a zenner diode on a power supply.
In some cases I really get negative voltage spikes as shon below.
What zenner diode you reccomend me to use?
how do ineed to put the diode to  eliminate them?
Thanks.

2

Power/Renewable Energy/EV's / Re: DIY Battery Bank from Recycled 18650

« Last post by ledtester on Today at 05:17:22 am »

What are those things in a glass package? Fuses?

3

RF, Microwave, Ham Radio / Re: Cascade RF Frontend 2.4GHz possible?

« Last post by Flunze on Today at 05:09:08 am »

Please see attachments for Front, back side and the circuit I want to use.

4

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by Bud on Today at 04:40:57 am »

LinkedIn web site is the text version of TikTok and a model of a garbage useless web site.

5

General Technical Chat / Re: Relay trigger when voltage above 13v

« Last post by ledtester on Today at 04:37:36 am »

Here is TI's app note on using the TL431 as a comparator:

Using the TL431 for Undervoltage and Overvoltage Detection
https://www.ti.com/lit/an/slva987a/slva987a.pdf

You might find it easier to use a real comparator - eg. a LM339 / 393 / etc.

Here is TI's app note on designing a comparator circuit with hysteresis:

Comparator with Hysteresis Reference Design
https://www.ti.com/lit/ug/tidu020a/tidu020a.pdf

6

Computers / Re: Format a 256GB pendrive with FAT32 using a windows 10 pc

« Last post by Bud on Today at 04:32:40 am »

It's often overlooked that the Windows GUI is a graphical shell sitting on top of a command line OS.

This has not been the case for decades, since Win98.

7

Other Equipment & Products / Re: Three most useful tools I got from AliExpress

« Last post by tatel on Today at 04:20:52 am »

I have to find the ProsKit desolder gun.  But it was about $100; bought it as a "first timer" on another account.  (Yes, I am that cheap!)

https://aliexpress.com/item/32957483227.html

8

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? perhaps a microphone) on the lid. I think the sensor on the lid is just used to trigger the solenoid.

9

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.

10

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.