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EEVblog Specific / Re: EEVblog #1155 - Mailbag
« Last post by Fungus on Today at 09:54:56 pm »
It's definitely pronounced "risk five" and not "risk vee".

See the official RISC-V website :
RISC-V (pronounced “risk-five”)

How about Apple OS-X?

General Chat / Re: How an EMC problem can kill people and a company
« Last post by Kjelt on Today at 09:54:49 pm »
Today the results of an independent investigation by TNO has been published.
Although I haven't seen or read the final report, the minister has continued the roadban for this vehicle.
The media say (translated from quote below)

TNO has conducted an investigation of the stint vehicle on six important vehicle safety points.
On all six points the vehicle failed the safety norms.
Problems can occur with the brake of the vehicle, the brakedistance en an uncontrollable acceleration of the vehicle can occurr where by the driver no longer has control over the vehicle.

Looks like the company can be blamed for not taking care of these issues.

Quote from:
TNO heeft de stint gecontroleerd op zes punten die belangrijk zijn voor de veiligheid van een voertuig. De stint blijkt op al die punten niet veilig. Zo komt het onderzoeksinstituut tot de conclusie dat er problemen kunnen optreden met de rem van de stint en de lengte van de remweg. Daarnaast kan er een "onbeheersbare versnelling" optreden, waardoor de stint als het ware op hol slaat.
Repair / Re: Fluke 75 piezo buzzer repair
« Last post by albert001 on Today at 09:54:20 pm »
Ok that's a idea just solder using a replacement 20mm disc with leads.

However the dmm and case are designed to  completely separate from each other, with no wires or attachments other than piezo disc contacts. So it would be better if I'm able to find some sort of material that works the same as the existing rubberized black conductive buttons. 

There are materials referred to as conductive rubber.

So far I've found a three types listed. 1. Multicon (oriented wire in either sponge or solid silicone) 2. Conductive Silicone (metallized filled silicones), and 3. Radthin (wire screen imbedded into silicone).

From eBay found a conductive silicon heatsink pad.

Uncertain if would have enough conductivity?

Test Equipment / Re: Current UK Oscilliscope prices...
« Last post by Fungus on Today at 09:48:30 pm »
I'd like an Analog Discovery as mentioned but I would probably kill it dead and the PC attached to it in 30 seconds flat.

Many moons ago I started with +-20V input scope and went straight to poking low power HV (plasma ball power sources etc) with x100 probe. No damages ever.

They're designed to survive "educational environments".
Test Equipment / Re: Current UK Oscilliscope prices...
« Last post by Fungus on Today at 09:47:27 pm »
I am a licensed radio ham (M0GZP) with a long term interest in electronics. I find myself in need of a new oscilloscope

It seems that my options in the UK at the end of 2018 are:

- £50: another old analogue scope (will probably last until I die of old age)
- £90: a handheld 40mhz scope that looks like a multimeter (similar to fluke portascopes of old?)
- £180: a cheap Chinese 100mhz 2 channel scope, with a 7” screen (any preferences in the cheap brands?  Hantek? Owon? Other?)
- £270: Rigol DS1052E, 50mhz 2 channel scope, with a small low resolution screen
- £360: Rigol Ds1054Z, 100mhz 4 channel scope, a 7” screen

The 1054Z is obviously the winner in terms of features and function.  But at twice the price of cheap Chinese I am not sure I will ever need the four channels.  That aside, is it twice as good?


The 1052E

Very long in the tooth now.

The Hantek or equivalent seems to me to be the front runner in terms of price/performance at the moment. 

Looks good in a brochure but the firmware/functions (ie. usefulness) are terrible.

I don’t know about the handheld thing, but they seem pretty impressive - and certainly portable!  I like the idea of having the scope with me when operating mobile, out in a field somewhere.

I don't know exactly which models you're referring to but usually very limited input voltage ranges, low bandwidth (not much more than audio), horrible to use (only a few push buttons for everything).

Have I missed any options in my “state of the union” above?  What thoughts/opinions do you have on my choices?

In the same price range as the DS1054Z there's a 2-channel Siglent and the GW-Instek GDS1054B. The GW-Instek is a bit more "analog" than the others and might be a good match for a ham-radio guy who makes amplifiers.

All can be bought online from places like batronix.
Well thank you for all your replies, that is what I already feared. I have actually already wound a first "transfomer" - albeit it's probably a pretty s*itty one, but it works so far for just testing the basic principles.

The only problem is: if I ever wanted to actually produce a small quantity product with it winding your own transformer seems like a bad idea and it's probably going to blow the BOM cost to have a custom transformer made for just 10-20 boards i guess.

However, for future reference and for whomever might stumble upon this post, I have found a pretty nice "smart transformer selector" by Würth Elektronik. I was actually able to find quite some transformers that could potentially suit the described needs of my first post. It can be found here:

Now back to winding my own transformers: are there any nice tricks to keep the wires nice and tight while winding the transformer? It always works pretty nicely while I am doing the primary, but as soon as I start the secondary the primary starts to "unwind" a little because I can not hold it in place anymore. Is it okay to glue it in place? Are there any common tricks I should know?
... as I fully intend to stop working ASAP. ... or SWMBO will kill me ...

Isn't there a large amount of contradiction and impossibility there?
Impossibility, contradiction and women, I have no problem with that statement  :-DD
The 34470A actually is even worse, 500pm +5x50ppm (50ppm of 100mA range translates into 250ppm at 20mA) in the 100mA range, so 750ppm. A relatively cheap way to go is to use a low TC shunt (1ppm or so, several resistors in parallel or a higher power one to limit self heating, e.g. VPG) with 500 Ohms and a 34465A, characterise that shunt every time with the 34465A prior to a session (to compensate for aging drifts), and measure the shunt voltage. You get the combined voltage and ohms measurement uncertainty, worst case add them up (RSS probably does not work as they are not fully independent of each other) and you end up with less than 100ppm/1a. need to do some calculation as the shunt will not exactly be 500 ohm (unless you trimm it before every session, which is not too complicated).
There may be meters who do it cheap at 100ppm/1a, but I am not aware of any from the top of my head and I would think it is pretty unlikely, other than the expensive ones (3458A, 8508A).
Test Equipment / Re: Current UK Oscilliscope prices...
« Last post by MrW0lf on Today at 09:39:51 pm »
I'd like an Analog Discovery as mentioned but I would probably kill it dead and the PC attached to it in 30 seconds flat.

Many moons ago I started with +-20V input scope and went straight to poking low power HV (plasma ball power sources etc) with x100 probe. No damages ever. Sometimes used ADUM4160 based USB isolator (use ext power to it!) just in case. USB 2.0 scopes will probably all work with these with some wfm rate hit.

Otherwise Siglent SDS1000X-E series is probably most balanced cheap scope. There should be no big surprises in regard to waveform shapes and amplitudes compared to say good analog scope.
Altium Designer / Re: Copy components from a file to another
« Last post by Agrum on Today at 09:35:46 pm »
Thanks  :-+
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