Recent Posts

31

Repair / Re: Desoldering advice

« Last post by shapirus on Today at 08:05:42 am »

Another method (or rather an additional step) is to use low melting point solder, or simply Rose's alloy, by adding it to the joints and letting it mix with the old solder. The resulting mixture will melt much easier.

But after the job is done you will need to remove all the remains of this low melt mixture as thoroughly as possible: you don't want it to compromise the new solder joints you make when you reassemble the thing.

32

Beginners / Re: buying a oscilloscoop

« Last post by pcprogrammer on Today at 08:01:44 am »

what about this scope good or not     https://www.eleshop.nl/rohde-schwarz-rtb2004-oscilloscoop.html?gad_source=1&gclid=CjwKCAjwuJ2xBhA3EiwAMVjkVIkTxkxw-RRv1b-6FZMK4SPThHQuZIQDMGKAdpAg6m9gnVzIk4lLdxoCP54QAvD_BwE

   That is a large jump in budget. 

Definitely a good scope with lots of possibilities, but overkill for what you stated to be doing with a scope. Only when you become a developer and start to make more challenging designs you would need a scope like that.

Like tggzzz wrote, we don't give our advice just for the fun of it.

33

Metrology / Re: 5.5D vintage Systron Donner 7205 DMM with 0.5% FS error

« Last post by Kleinstein on Today at 08:01:13 am »

A bit strange for a dual slope ADC the integrator uses different resistors for the input and reference currents. So the gain may drift with R88 and R89, though this should be pretty accurate ad good resistors.
The integrator is also unusual in that the signal is applied to the positive input and the integration resistors towards ground or the references.

An easy point to check could be if there is leakage from VR6,VR7 , that may attenuate the signal before it reaches Q13.

Is the 0.5% FS error the same for the positive and negative side ?  Another point to check could be the gain at some 50% of FS, as the error at full scale could also be a linearity issue.

34

General Technical Chat / Re: Do you think an LED is a resistor?

« Last post by DenzilPenberthy on Today at 07:59:58 am »

This thread is a truly dumb premise.  So what OP is saying is that literally every single electrical/electronic component that exists is a 'resistor' and that's somehow a useful or interesting observation?

Presumably OP would even pedantically call a superconductor a 'resistor' just 0 Ohms?

This is the same sort of person who spends the whole evening in the pub with friends strenuously arguing that breakfast cereal is a type of soup.

35

Other Equipment & Products / Re: Ring light for microscope

« Last post by jfiresto on Today at 07:55:27 am »

That may be the way to go. My hope is not to do that as I would like to keep the lens and filter you can presently insert between the lamp and inlet.

36

Repair / Re: Desoldering advice

« Last post by nvmR on Today at 07:55:20 am »

For TH devices, use a solder wick or solder pump to remove the solder from each and every leg individually.
You can also try to place a heat plate beneath the pcb, and give it a preheat.
A large blower can also give a good preheat.

37

Microcontrollers / A couple questions about Milk-V Duo boards

« Last post by SiliconWizard on Today at 07:52:50 am »

Interested in evaluating the CPU they use. I haven't ordered boards yet.

Does anyone know:
- How the C906 core compares to say a Cortex-M7 (namely the main C906 core @1GHz vs a iMXRT10xx @600MHz, for instance)?
- The approximate current draw under typical load, and any "sleep" mode it may have?
- Whether it's possible (probably) but, most of all, documented, to program the main core baremetal (no Linux)? If so, is there any documentation out there? (I've seen the typical setup was Linux on the main core and some RTOS on the second core, I'd like to use both cores baremetal).

Thanks!

38

General Technical Chat / Re: Is VAT number needed when ordering from Arrow USA?

« Last post by jc101 on Today at 07:47:22 am »

Obtaining a VAT number is free. 
Using one is the admin cost of keeping track of the VAT in purchases and sales, filing the quarterly return and paying the bill.

Whatever you sell, in time or goods, costs your customers 20% more. If they are VAT registered, they can claim that back, but if you sell to the general public, you have become much more expensive.

39

FPGA / Re: ATF1502 programming & 'wrong' id (fake?)

« Last post by oPossum on Today at 07:47:14 am »

I don't know if the ID is valid and parts are genuine but Silicon Storage Technology (SST) is part of Microchip.

40

Other Equipment & Products / Re: Pace ADS200 soldering station

« Last post by pope on Today at 07:43:54 am »

So Steve's been lying to us all along.

Why would he?