Recent Posts

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1
FPGA / Re: Detect Protocol on bus
« Last post by senso on Today at 09:13:03 pm »
Use a pin, or a couple to give an ID to each cable, now it just knows the protocol based on the cable that is plugged in.

Or just use a couple positions/connectors, and each position is one protocol.
2
RF, Microwave, Ham Radio / Re: NanoVNA Custom Software
« Last post by radioactive on Today at 09:06:01 pm »
Anyone else think that the need for better than 40dB for an S11 measurement might be a post for the Metrology thread?   The description could be changed from "This is where the Voltnuts hang out."   to  "This is where the Voltnuts and S11nuts hang out".   
3
Beginners / Re: LM324 Power Supply with variable voltage and current
« Last post by xavier60 on Today at 09:04:49 pm »
3A is the maximum output current, I do not have a resistor or a group of resistors which draw exactly 3A, can I use a load of 2.66A ?
Or should I test with a short circuit on the output ?
2.66A is fine. Don't allow it to go into current limiting.
4
Beginners / Re: LM324 Power Supply with variable voltage and current
« Last post by mike_mike on Today at 09:02:14 pm »
3A is the maximum output current, I do not have a resistor or a group of resistors which draw exactly 3A, can I use a load of 2.66A ?
Or should I test with a short circuit on the output ?
5
Beginners / Re: LM324 Power Supply with variable voltage and current
« Last post by xavier60 on Today at 08:58:38 pm »
Should I install R32 (100R) and start testing again ? If yes, then which tests need to be made again ?
Definitely fit R32, having B-E bleed resistors is good design practice.
You should test the voltage overshoot while unloading from a 3A normal load, before and after R32 is fitted.
6
I'd like to make micro-reflow device for hobby, and the most difficult is to invent how to mount MCH heater on PCB and protect PCB from heating. Of cause, solution should be simple & easy to repeat by anyone.

First attempt was to use "chineese aerohel" from aliexpress. It's not convenient material (too many dust), and insulation is far from ideal. Also, it causes too slow cooldown.

Second attempt was to use air space and reflector. Since bottom convection is very low, we should mostly care about IR waves.



Heater sits on cone bolts in brass insets. Physical contact is very  small. Base PCB is covered with "acrylic glass" film for bathrooms :).

Better, but still not enougth. On the way - additional cover of heater bottom with reflective paint (i'm waiting until paint dries, but preliminary result is very impressive). Then, will try to make separate reflective surfacebetween PCB and MCH.

Question 1.

Do you have ideas how to mount MCH on PCB with good thermal insulation and low height?

Question 2.

Since i need equal temperature on all surface, about 10mm of plate from each side become useless (checked by thermal imager). Only 30x30mm left. Not bad, but i'd like to improve.

Idea is to attach Panasonic PGS sheet on top. Can you advice glue for that? Ideally, with up to 400C operating temperature, available on aliexpress or ebay. If that's impossible - up to 300C.
7
...you just cannot have the high end electronics if you abandon the low end stuff like eg  basic SMPS design for consumer products.,.,......it just doesnt work like that.
That's nonsense. Most engineers who have only developed high end electronics have skills which work fine for those types of product, but have no idea how to be competitive with low end stuff. Driving every last cent out of the BOM is far more critical in low end designs, and is a skill set in itself.
8
Well, I couldn't wait so I inserted a SIM card ... and it doesn't work. Even though the error messages point at the SIM card I believe it is the phone that is locked.

Firstly it says
Quote
Invalid SIM card
Network locked SIM card


The, after some more steps I get the message
Quote
Enter network unlock code
_________________________
( ) Unlock ( ) Dismiss

Since the SIM card is fine I tend to think the problem is the phone is locked to AT&T, even though they told me it was unlocked.

I am guessing the "Network unlock code" would be from AT&T to unlock the phone. Right?

I think I should be able to get it without problem but, if not, I assume I can get it unlocked by other means.

Any comments about this?

9
General Chat / Re: What did you buy today? Post your latest purchase!
« Last post by Terry01 on Today at 08:54:19 pm »
Ive been wanting one for ages but just never got round to ordering 1! Looking forward to learning how to drive it!  :)

Good for you it's a lot of fun!  :-+

I've seen lots of reviews that say the same thing. 
Even just getting a few LED's flashing at different speeds was very satisfying. I'm looking forward to learning to do more and more with it.
10
Repair / Re: Pressure washer keeps tripping breaker
« Last post by james_s on Today at 08:52:12 pm »
I would monitor the running current, and then figure out what else is on the same circuit. The startup surge should normally not be an issue.
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