Low Cost PCB's Low Cost Components

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Don't understand the confusion over risk of buying a used CRO :o
What a lot of people are forgetting, is that if the seller claims that the scope was tested and works, there is little risk. If you are a beginner, don't buy an as is scope. Fixing them can be dangerous if you don't know what you are doing. All the negative attention in these threads regard the risk of buying a AS IS scope. Buy a TESTED WORKING scope like I did, and you will be fine.

Beamin, if you live near universities, ask them if they do not need/are chucking their old oscilloscopes. I did, got a 2235 for free. A free working CRO is better than no scope. :-DD
Test Equipment / Vellerman WFS210 wireless oscilloscope for only £20 !
« Last post by Fraser on Today at 07:33:45 AM »
I was looking for a very simple oscilloscope that could connect wirelessly to a Apple or Android tablet.

A quick look on ebay revealed the Vellerman WFS210 being sold cheap for around £30. Then I found it available for £20 from the Maplin Electronics eBay outlet.

The WFS210 manual is here


The software runs on A PC up to Win7, iOS tablet and Android tablet..... but not on phones.

The unit does have its issues. Not particularly high sample rate but for simple low frequency scope and DVM measurements it will be fine. It is self powered and wireless, so pretty useful.

I bought one to test. Hopefully it will connect OK to my PC and one of my tablets. At £20 it seemed to good to ignore.

Hello folks,

I've been pondering this lately and I'm sure there's someone here with experience in this field. So we know that the charging circuitry in modern smartphones charges the Li batteries inside with constant current up until some voltage and then switches to constant voltage charging. The problem I'm having is with the current limit on the USB 2.0 ports on your PC which are limited to 0.5A, 5V (2.5W). So suppose we're capable of charging our Lithium cells at 2A and our current battery voltage is 3.6V and we're charging in constant current mode. This means that we can supply ~ 7.2W. Assume it's 100% efficient.

As you can see this presents problems. The input is limited in power. So how does the charging circuitry inside the phone KNOW how much power it can draw before the input supply droops?

I hope this is clear...

Repair / Re: Hard disk recovery
« Last post by Toasty on Today at 07:29:53 AM »
No issue other than you may have 2 bricked drives after that, both failed drive and corrupted donor board.

In my experience, I've never had that issue.  The controller is not "written to" unless you flash it.

I've swapped boards between hard drive "model number" matches and had "not recognized".  But when using identical, as I described, there are no issues.

General Chat / Re: Why do I already not like Star Trek Discovery?
« Last post by rdl on Today at 07:29:50 AM »
I guess a lot of other people had the same idea.

Star Trek: Discovery is getting pirated a lot
Programmer works in Win10 64 bit and so I believe it should work in Win7 too. Might be something in your settings and not the programmer software. Why not D/L a new copy of the Windows software and reinstall it. 
Beginners / Re: Unregistering
« Last post by hermit on Today at 07:25:13 AM »

He who must not be named had asked Dave to remove him, so I guess this can be done.

Sounds like an interesting story - can you elaborate?

Repair / Re: Hard disk recovery
« Last post by Electro Detective on Today at 07:24:13 AM »

...Press the hard drive to your ear and apply power.  Any noises other than spin-up and a brief head movement?  No grinding or clicking!

...PS: Could the BIOS have been reset to AHCI where it was SATA?  I've seen that cause an unrecognized drive problem too.

 :-+  Beat me to it    :clap:

I've never seen or heard of a clapped out PSU taking out drives,
just a loss of DC power to the drives

Try the suspect hard drives on another computer or hook them up via a USB adapter

Good Luck   :)

I use plastic spring clamps to make a tripod, but for anything that is likely to need a more strurdy or permanent connection, I get the hot pointy thing out and add a short through-hole component lead I can clip on to.

For high speed probing I make up a coaxial spring setup for ground and testpoint out of wound through-hole component leads so that the probe can be slipped in.

For differential high speed probing such as USB HS speeds and above, it’s typically a jury rig with elastic bands and/or kapton tape to hold the bulk of the probe and judicious tip browser adjustment. If the signal is designed to run over a cable, I make up a very short M/F breakout to intercept the signal where I can probe.

Test Equipment / Re: Test Equipment you didn't know you needed
« Last post by HighVoltage on Today at 07:19:01 AM »
Even more expensive than the source meters are the electrometers

I just got a Keysight B2987A and before I had one I did not know I needed it.
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