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 21 
 on: June 01, 2020, 04:47:24 16:47 
Started by Parmin - Last post by dennis78
@pickit2

Which FET's you used?

 22 
 on: June 01, 2020, 04:13:38 16:13 
Started by Parmin - Last post by Ahmad_k
When you say switchmode power supply that's mean you should feed the input with DC current, then use a stepdown or boost converter.

What you want is feeding an AC signal from 90to 240 and get AC signal 24V 200W ?

The question is: what kind of load are you using ? Sensitive to harmonics ? is it inductive load ?

Another approach to pickit2 design is to use TRIAC or dual SCR (Resistive load only)

 23 
 on: June 01, 2020, 04:06:29 16:06 
Started by TucoRamirez - Last post by TucoRamirez
hi, i'm trying to save data on a usb stick using a nucleo L4 board, the L476RG

I followed tutos from the net about setting up the mess... but most of them are focused on the STM32F4-duisco board (with some extra circuitry to drive Vbus and id pin)

The nucleo board has no circuitry at all as the discovery board, and i dont have the same spare components right now to try to build that blocks of VBUs Vsense and id circuitry


my questions are:
*  have you already tried to make the  usbhost mode with L4 family?
* I'm forgetting something about the necessary VBUS sensing pin? (by now i'm holding it to a constant level as it can support >3.3V)
* My code runs until MX_USB_Process(), then it's stuck on Appli_State= APPLICATION IDLE (so my usb sitck is not recognized)
* I tried the STM32F4 disco board and my usb memory is read and etc but i wonder how minimal can be my setup to make the usb work on the L4 nucleo (board powered by the 5V stlink line from the debug connector)



thanks in advance.


 24 
 on: June 01, 2020, 02:49:49 14:49 
Started by Parmin - Last post by pickit2
I done a project a few years ago.
it was 240v ac to 120v ac
it had two 600v power FETS back to back
hand full of diodes and caps to make a dc supply to control the fet gates
I used a small transformer in the finished unit, to power a few other things.
the idea is the fets are used as a power resistor, the voltage controlled via the gates.

without getting out of this lock down I can't get in to works.
but maybe you could get a prototype working easily
concept drawing

 25 
 on: June 01, 2020, 10:41:03 10:41 
Started by CortexM0Inside - Last post by CortexM0Inside
Probably not too many people have heard of Chinese manufacturer GigaDevice who so far has mostly been known as a NOR Flash memory manufacturer. Their GD32 range of MCUs is however STM32-compatible, making them interesting (cheaper) alternatives to sourcing directly from ST. Now GigaDevice has announced during a presentation that they are releasing a range of RISC-V-based MCUs: the GD32V series.

As GigaDevice has not yet updated their English-language website, the information we do have is based on CNX-Software‘s translations from Chinese. The specs for the GD32VF103 series of MCUs are listed by them as follows:

    Core – GD32VF103 RISC-V “Bumblebee Core” @ 108 MHz
    Memory – 8KB to 32KB SRAM
    Storage  – 16KB to 128KB flash
    Peripherals – USB OTG and CAN 2.0B
    I/O – 3.3V, 5V tolerant
    Supply Voltage – 2.6 to 3.6V
    Package – QFN36, LQFP48, LQFP64, and LQFP100 packages

Whether they are pin-compatible with the GD32 MCUs is still to be confirmed. If that turns out to be the case, then this might be an interesting drop-in solution for some products. From the specs it seems clear that they are targeting the lower-end ARM-based MCUs such as ST’s Cortex-M3-based STM32F103, which are quite common in a large range of embedded systems.

Seeing a performance comparison between both types of MCU would be interesting to see as lower power usage and higher efficiency compared to the ARM cores is being claimed. Both MCUs and development boards are already available for sale at Tmall, with the basic GD32VF103C-START board going for about $11 and the GD32VF103TBU6 MCU (QFN36, 64 kB Flash) for roughly $1.27.

Documentation and SDKs in English seem to be a bit scarce at this point, but hopefully before long we too will be able to use these MCUs without having to take up Chinese language classes.

Reference : https://hackaday.com/2019/08/27/gigadevice-releasing-risc-v-mcus-and-development-boards/

Posted on: June 01, 2020, 10:30:51 10:30 - Automerged

Checking @ datasheet (http://www.gd32mcu.com/data/documents/shujushouce/GD32VF103_Datasheet_Rev%201.1.pdf)
GD32VF103 is pin compatible with STM32F103
This is really good for GD32VF103 based blue-pill/black-pill board to gain real good popularity.

But I still don't know whether IAR EW FOR RISC-V support's GD32V micro-controller family.

 26 
 on: June 01, 2020, 10:14:44 10:14 
Started by PM3295 - Last post by vern
Quote
Definitely not 121 dBuV into 50 ohms
I disagree, if it can deliver 121 dBuV into a 50 Ohm antenna, it will deliver the same power into a 50 Ohm load if that load is suitable for the frequency.

Quote
that output voltage is presented to a matched antenna (which will have a much higher impedance)
50 Ohms is 50 Ohms

 27 
 on: June 01, 2020, 10:13:11 10:13 
Started by Parmin - Last post by Sideshow Bob
What are your input voltage range and type. And what is your output frequency range? Not that important but is your AC output at 24 volt RMS or peak/peak to peak. Also what kind of accuracy do you need for the output

 28 
 on: June 01, 2020, 08:07:58 08:07 
Started by Parmin - Last post by kripton2035
I was also searching for something like this, but to make an enough powerfull variac in a small size.
a mains AC to mains AC variable power supply. they are really expensive.
and I did not find any online schematic for this.

 29 
 on: June 01, 2020, 02:35:16 02:35 
Started by Parmin - Last post by bigtoy
It is possible. It's called an AC to AC Converter (google, wikipedia, etc). But not very common. For lower powers a transformer is typically used. For high powers oddly enough a motor driving a generator is sometimes used. If you look at a rectifier (AC to DC converter) it's typically 2 stages: a PFC stage followed by a DC-DC. The output of the PFC is DC (or an approximation thereof), so you can see the issue. I don't know where to find something off-the-shelf like what you're looking for, unless you accept either a transformer, or a rectifier followed by an inverter (basically a strange UPS variant without the batteries).

 30 
 on: June 01, 2020, 02:22:43 02:22 
Started by Parmin - Last post by Parmin
Hey guys,
I wonder if there are any AC output switchmode power supply?
Or is it even possible?

I am needing about 200+ units of 24VAC 200W output power supply.
I guess I can perhaps add a DC to AC converter to a DC output unit but this would make the design much more complex.

I understand that I can use a simple transformer for this, however,
the reason for switchmode is for it to be lightweight and they are usually able to input 90 to 265Vac.

Anyone can send me in the right direction?

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