Recent Posts

1

Beginners / Re: LM317 Based Digitally Controlled Power Supply

« Last post by Zero999 on Today at 08:28:08 am »

The circuit with the LM317 as a power transistor replacement would need a negative supply for the OP-amp. Otherwise it would not work below some 1.2 V and could not limit the current with these low voltages (e.g. with a short).

Yes, you're right. I somehow messed up by copying the wrong schematic.

I'll edit it.

2

Beginners / Re: Signal Edge (high and low) Validation and Counter - sharing Arduino/C++ Code

« Last post by gnif on Today at 08:26:18 am »

Duplicate post: https://www.eevblog.com/forum/microcontrollers/signal-edge-(high-and-low)-validation-and-counter-sharing-carduino-code/

I removed the duplicate, unlocking this thread.

3

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

« Last post by Zero999 on Today at 08:24:56 am »

The LM386 is an audio amplifier IC. I think you meant the LM393.

Plenty of good ideas have been given above. If you want an off the shelf solution, then you could use a voltage monitoring relay.

4

Beginners / Re: Signal Edge (high and low) Validation and Counter - sharing Arduino/C++ Code

« Last post by Halcyon on Today at 08:24:53 am »

Duplicate post: https://www.eevblog.com/forum/microcontrollers/signal-edge-(high-and-low)-validation-and-counter-sharing-carduino-code/

5

Manufacturing & Assembly / Re: Brief review of the Zhengbang ZB2520HL reflow oven (T-962A alternative)

« Last post by Kean on Today at 08:23:07 am »

Cheap IR heater ... no thanks. might be okay for some easy PCBs without special requirements. And no one can convince me that unshielded IR will be good (or good at all for components).
Conventional is much less troublesome, the next level of that seems to be Vapor Phase Soldering.

One of those IR modules probably costs around 5-7$ (just that you know what the engine of that IR heater costs). Multiply it with 4 and that's it the rest is enclosure and the controller.

I'm not sure why you post these negative comments all the time.  If you really think the cost to build, market, and support these is so small, then you should be able to make a very profitable business selling your own "perfect" design...

Most owners of these ovens seem to agree they do a fine job, much better than other cheap ovens like the Puhui range.  And not everyone has the time or tools to construct a DIY reflow oven.  I've built one using a Reflow Master controller, but the toaster oven I used is crap and I didn't want to waste more time on perfecting it.  I just use it for low temperature part drying/baking now.

6

Other Equipment & Products / Re: Pace ADS200 soldering station

« Last post by Shock on Today at 08:20:24 am »

There is a true two-channel AT420 hot tweezer with some 160 Watts. PACE has no such hot tweezer.

According to JBC they have no such hot tweezer either.

160W exceeds the DI, DDE and DME rated channel power. The DI is only 130W total, the DDE (a 2 channel station) rated 190W total, based on that alone I would not be claiming "true two-channel" or "160W" anything.

7

RF, Microwave, Ham Radio / Re: fake MPF102s from AliExpress

« Last post by Solder_Junkie on Today at 08:17:08 am »

I was searching for an SMD replacement for MPF102. The one I found that (based on specs) seems to be close, and was available at LCSC, is an OnSemi MMBFJ309LT1G. I have not yet had the time to verify their utility for this purpose.

Enigma Components stock a Motorola/Fairchild MMBF102, eBay part 126423215717
Enigma are based in the UK, I have bought from them in the past and they are good people to deal with, not sure about posting to the USA though:
You can shop directly with them, inc a datasheet for the '102 at https://enigma-shop.com/

73 SJ

8

Microcontrollers / Re: STM32H7 CortexM4 USART DMA issue

« Last post by Diego_2024 on Today at 08:16:37 am »

what is RTS? seriously?

9

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

« Last post by tautech on Today at 08:15:45 am »

With mouse plugged into the scope the scroll wheel is available for making numeric field adjustments.

That's interesting, must not have implemented that in the web interface

Can we ask the FW version in your unit ?

10

Beginners / Re: Blocking Phantom Power 48V from Audio output

« Last post by Saimoun on Today at 08:14:12 am »

A very thorough analysis is here, in AES Convention Paper 5335:

https://www.thatcorp.com/datashts/AES5335_48V_Phantom_Menace.pdf

Have a good read.
See page 11.

Both very good read thank you! Though they only seem to cover the Phantom Power source protection, i.e. the mixer/audio input side.

I'm on the other side, I have an audio output which may or may not receive phantom power. Are you saying I should simply implement their proposed protection on my opamp's outputs?



I understand the 1N4004 diodes to the rails, though I am not sure I get what R4, R5, and RG are (I believe they are just part of the audio input - my design is an opamp output). And what about the capacitor, would my little 6.3V cap not be in risk of damage while the plug is connected/disconnected?

Thank you!