Recent Posts

1

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.

2

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.

3

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

4

Microcontrollers / Re: STM32H7 CortexM4 USART DMA issue

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

what is RTS? seriously?

5

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 ?

6

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!

7

Projects, Designs, and Technical Stuff / Re: LPC-bus chip at less than 33MHz

« Last post by RoGeorge on Today at 08:12:53 am »

Turns out I was overly optimistic. 
After reading the datasheets:

- the sound CODEC (ALC201A) is not I2S, but AC-Link (AC'97).  At least it works at 3.3V (same as the RPi IOs), but it needs 5V, too, for its audio out.  There is a 78L05 onboard (to reduce the digital noises that might be on the +5V digital power) so the sound chip will need 3.3V and a 12V, too, or maybe a charge pump voltage doubler to get 10V from 5V.  ALC201A has its local quartz oscillator, so the audio data clock must be 12.288MHz (half of the 24.576MHz quartz).

- the super IO chip (IT8705F) is working at 5V (the PCI bus of that motherboard, where from the chip was cut, was at 5V), not at 3.3V, like Raspberry PI, so it will need bidirectional level shifters (the LPC bus has 4 data lines and 2 control signals minimum).  The 24.576MHz clock from the sound chip is for the ALC201A only, so the super IO chip IT8705F will need its own 24MHz / 5V clock.

8

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

« Last post by Kean on Today at 08:11:11 am »

Hi.
I just collect my RF-A350 oven, I did not try any PCBs yet but when I checked build in reflow profile without any modifications and with thermocouples stick to bottom plate it doesn't look good.
Temperature in the middle is follow the profile but overshoot 5-6 deg. Temperatures 10 cm from middle, each side, seems to also follow profile but are under the line sometimes 10-15 deg, but within few extra seconds they starts following middle temperature.
Can someone share settings or other tweaks for this oven as factory one seems to be not perfect.

Attached factory profile 4 with empty tray.
Regards

I've not done any tweaks, just been using curve 4 and getting good results.  It works so much better than my 6 year old T-962A which would either burn connectors or not fully melt the solder, both happening on the same PCB unless is was really small and placed close to the center of the tray.  I've not run any large inductors, but I've had some batches with various SMT inductors, relays, electrolytic caps, and connectors go through it fine.

You really need some thermal mass and the thermocouples attached to that to get any real sense of how well it follows the profile.  I did a trial run some time ago with a temperature logger, but I don't seem to have saved the data.  I'll have to do that again when I get a chance.

The curve I posted above as measured by the ovens own thermocouple was pretty accurate to the settings - it will never be perfectly even in every part of the oven.  You can see it did overshoot a little at the start of the soak phase.

I sit my pcbs on small metal standoffs under the corners or edge rails to keep the PCB slightly above the tray.  Possibly not as critical as on the T-962A which just had bare metal.

9

Test Equipment / Help me chose my pogo pin for THM Test Points on my PCB plz

« Last post by fishywisky on Today at 08:10:39 am »

Hello everyone,

I have a slight problem. I'm in an internship and don't know much about Pogo pins. I wish to select a type to come and touch the THM test point on the board that is given to me. The test points look like the ones in the linked picture. If anyone could help me, it would be really nice.

Have a nice day!
(Sorry for my poor English)

10

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

« Last post by vk4ffab on Today at 07:59:48 am »

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

My gut says, nope, bad idea. The RF in and Antenna ports have maximum ratings of 5dbm into them and you want to blast almost 1/2 a watt into it. The output power from one of those chips should be 22dbm. BOOM dead chip. Just buy a new router.