Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Yeah... the difference there is the difference in price. That one costs 4X as much as this little one. You can spend all sorts of money, depending on the features you want. I just got it because cheap as chips, and I'm already familiar with the kind of work they're talking aboot with my ESCs and PDBs.

If I let the magic smoke out, well... lesson learnt cheaply enuf. 

mnem
 

[tautech]

Edit: I did my homework before ordering and got the "Wise Maple" version that doesn't need to be fixed and should be working out of the box.

Did you ?
K Weld:
https://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/

[Kosmic]

Yeah... the difference there is the difference in price. That one costs 4X as much as this little one. You can spend all sorts of money, depending on the features you want. I just got it because cheap as chips, and I'm already familiar with the kind of work they're talking aboot with my ESCs and PDBs.

If I let the magic smoke out, well... lesson learnt cheaply enuf. 

mnem
 

probably not 4x. I paid 20$ shipped. I'm still waiting for it though 

[Kosmic]

Edit: I did my homework before ordering and got the "Wise Maple" version that doesn't need to be fixed and should be working out of the box.

Did you ?
K Weld:
https://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/

Yeah not exactly the same category of product (kWeld kit is 159 eu buck). I was looking for a dodgy one that might blow up.

[mansaxel]

Can anyone round here give me a well-founded recommendation for a model or maker of a portable voice recorder (aka solid-state dictaphone)? Should take standard batteries and have a line-in.
Should also produce standard file format and have a interface of some sort.

The obvious answer in gear-head-land is the Nagra.

People who record music and can't afford the Nagra swear by the various Zoom recorders; the most likely in your scenario whould be the H1N, but I'd raise the bar and say that the H4N is about right. XLR inputs is a must on anything that records.

If you really want only a dictaphone replacement, there are a bunch of Olympus recorders that are very affordable and compact; you might have to search a bit for Line in, though.

In Germany, the Thomann store probably is the most economical way to get hold of these devices. I'm a happy customer -- haven't bought any recorders, but a piano and lots of sundry pro-audio items.

Edit: "Standard size batteries" (I'm thinking you mean a bunch of AAA or similar) is not a feature of these, as far as I can tell. Cheap built-in rechargeables have seen to that.

[McBryce]

Update on the state of the Avo paint removal, my son has worked his socks off today on the front panel using rubbing alcohol and cocktail sticks with the occasional use of a very fine flat screwdriver and I had a go at the side using a dremmel and small bristle wheels. As these before and in progress photos show, my method seems to be marking the plastic case while sons doesn't. I'm not too bothered by the side and also the top (not shown) as I plan to give the case a lick of matt black paint which will hopefully hide the polishing effect of the bristle brush wheels.

I think the touching up the front will require is the white lettering of the terminal posts will require the embossed letters replacing, my son is good at that as well.

The meter is coming around and looks far better as a result, I'm really chuffed with the meter, this ones a keeper for sure, more paint removal later in the week for sure.

Toothbrushes are excellent for cleaning these types of surfaces. Just remember to clean the toothbrush carefully afterwards, otherwise the wife will notice that you borrowed it for something else.

McBryce.

[Robert763]

Just put two 1A fuses in series!   

Don't laugh, sometimes this almost makes sense. I've seen meters where an expensive, slowish high breaking current fuse is placed in series with a cheap, faster equally rated fuse with relatively low breaking capacity (typically a 20mm glass fuse with circa 80A breaking capacity). The idea is that "typical" mishaps cause the 10p glass fuse to rupture, you replace it and move on. In the case of serious fault current from a low impedance source that's enough to turn the contents of the glass fuse into a conductive plasma only then does the expensive fuse (like the classic £10+, 11A, 1000V HRC ones with a 20 kA breaking capacity in Fluke DMMs) come into play and use up its breaking capacity in one short bang. It's a good trick for saving money (or at least servicing costs) while maintaining safety.

Many years ago I designed a circuit for that ran off a 28V DC supply. At the supply input it had a 3.15A 20mm fuse followed by a 33R 25W  and a 33V 10W zener to qround. The aircraft supply had a 1A circuit breaker and the whole system drew about 200mA. All done and fitted. A few years later, after I'd left the company, I got a request for a "firmware" update (actully just a look-up table in PROM, no micro processor in the unit). I asked for a unit so I could check the change. I found that the unit had a 0.5A fuse fitted. On enquiry they said someone had looked at it and the 3.15A fuse would never blow so changed it. I said "go read the design and approval file" and they issued a SB to check all the units in service and change lower current fuses to the 3.25A type.
A virtual cookie to anyone who knows why the 3.15A fuse was fitted.

[Robert763]

My Budget is below £100, which would rule out new scopes & the common Fluke/Philips & Tek ones mentioned previously. It's mainly to fill a gap in portability, a few months ago I was talking to a work colleague who was having car problems (old 90's Ford) and was asking for advise, I couldn't help as I haven't got the right TEA to properly diagnose the electrical fault.

Anyway, I would probably be best to find something that will take regular alkaline batteries as it probably wouldn't get used often, I think it would be easier to remove the batteries when not needed and not have to worry about them. Vintage scopes would be OK too, as I'm more likely to be able to repair older stuff without SM parts.


David

Stewart of Reading are advertising Fluke 97's for £75 that will just about hit your budget with VAT and post. They have 99b's for £125.

[Robert763]

Can anyone round here give me a well-founded recommendation for a model or maker of a portable voice recorder (aka solid-state dictaphone)? Should take standard batteries and have a line-in.
Should also produce standard file format and have a interface of some sort.

Olympus

[Robert763]

<SNIP>

I ordered something awfully similar. I'm planning to use it to make Type K thermocouple. I should also try to find some nickel strips to see how well it's working on batteries.

Edit: I did my homework before ordering and got the "Wise Maple" version that doesn't need to be fixed and should be working out of the box.

If welding thermocouples you need a carbon electrode. Using the copper or brass ones suppled with battery tab welders contaminates the alloy and can lead to inaccuracy.
 

[Vince]

The aircraft supply had a 1A circuit breaker and the whole system drew about 200mA.
A virtual cookie to anyone who knows why the 3.15A fuse was fitted.

Maybe the 3.15Amp, according to the manufacturer data sheet that you no doubt studied closely, would blow at a much lower current if given a long enough time, and you wanted to use that sluggish effect to allow for transients higher than 200mA  to not trigger the fuse, as part of the normal operation.

I really don't know so please do tell !

BTW I don't even want the cookie, I am on a diet at the moment ! 

[Brumby]

Courtesy of a fellow member here, I now have replaced the damaged button caps on two units of my HP test gear:

The power button of my 3478A (purchased with damaged button)


and the green POS/NEG button in the delay section of the 1740A I scored from Dave.  (The damage to the button was through my clumsiness.)


My thanks to lowimpedance!!

[Specmaster]

Just put two 1A fuses in series!   

Don't laugh, sometimes this almost makes sense. I've seen meters where an expensive, slowish high breaking current fuse is placed in series with a cheap, faster equally rated fuse with relatively low breaking capacity (typically a 20mm glass fuse with circa 80A breaking capacity). The idea is that "typical" mishaps cause the 10p glass fuse to rupture, you replace it and move on. In the case of serious fault current from a low impedance source that's enough to turn the contents of the glass fuse into a conductive plasma only then does the expensive fuse (like the classic £10+, 11A, 1000V HRC ones with a 20 kA breaking capacity in Fluke DMMs) come into play and use up its breaking capacity in one short bang. It's a good trick for saving money (or at least servicing costs) while maintaining safety.

Many years ago I designed a circuit for that ran off a 28V DC supply. At the supply input it had a 3.15A 20mm fuse followed by a 33R 25W  and a 33V 10W zener to qround. The aircraft supply had a 1A circuit breaker and the whole system drew about 200mA. All done and fitted. A few years later, after I'd left the company, I got a request for a "firmware" update (actully just a look-up table in PROM, no micro processor in the unit). I asked for a unit so I could check the change. I found that the unit had a 0.5A fuse fitted. On enquiry they said someone had looked at it and the 3.15A fuse would never blow so changed it. I said "go read the design and approval file" and they issued a SB to check all the units in service and change lower current fuses to the 3.25A type.
A virtual cookie to anyone who knows why the 3.15A fuse was fitted.

Protection against the 33R 25W resistor or the 33V 10W zener becoming short circuited on the incoming supply side. I'm guessing here that the I2T of the 1A breaker would mean that without the 3.25A fuse fitted, the energy let through would have destroyed your circuit. In other words you coordinated the fuse and breaker to discriminate against each other in order to allow the fuse to let go before the breaker did. 

[Robert763]

<SNIP>
Protection against the 33R 25W resistor or the 33V 10W zener becoming short circuited on the incoming supply side. I'm guessing here that the I2T of the 1A breaker would mean that without the 3.25A fuse fitted, the energy let through would have destroyed your circuit. In other words you coordinated the fuse and breaker to discriminate against each other in order to allow the fuse to let go before the breaker did.

Nope, even with a shorted zener the current was only a nominal 850mA so 23W is OK for the resistor. The CB would not trip either.
Bit of a trick question, the answer is to do with approval, not electronics. The unit was a fuel gauge signal conditioner, As it connects to the fuel tank it has to be incapable of causing ignition. Normally for aircraft kit this is done by testing in a chamber full of explosive gas / air mix (RTCA DO-160 section 9). There was a long wait for testing so I decided to do it by proving it was intrinsically safe by analysis. Thhis was based on an industrial standard for intrinsically safe equipment. One of the requirements of the standad was thet the input of the equipment was protected by an approved sand filled fuse. The lowest rating of fuse covered by the approved specification was 3.15A. About the only time it would blow is if the wirewound metal clad resistor shorted to case (never seen it happen and the WH25 resistor is rated to 3kV) or you connected the unit to 115V 400Hz (the specific aircraft didn't have that).
Much to the surprise of the "old hands" who insisted you had to test, the CAA accepted my approach and analysis.
The ciruit was unusual for the time (mid 80's) with ainput ADC addressing a look-up table of tank errors in a PROM with the data driving an DAC and analogue meter. This was more time saving. Typically at the time the tank sensors were non-linear and specific to their position in the tank. I used of the shelf linear sensors.

[Vince]

Thanks for sharing, much interesting 
I just quit aviation last week when I got fired... only got to see that bad side of it... tripping on tools and people in a crowded / overpopulated deck with missing floor tiles all over the place.  Fell through the floor, damaging my leg and spine for ever. Decided I was done with it and left... now trying to get back in the electronics industry instead, much safer ! 

[AVGresponding]

Just put two 1A fuses in series!   

Don't laugh, sometimes this almost makes sense. I've seen meters where an expensive, slowish high breaking current fuse is placed in series with a cheap, faster equally rated fuse with relatively low breaking capacity (typically a 20mm glass fuse with circa 80A breaking capacity). The idea is that "typical" mishaps cause the 10p glass fuse to rupture, you replace it and move on. In the case of serious fault current from a low impedance source that's enough to turn the contents of the glass fuse into a conductive plasma only then does the expensive fuse (like the classic £10+, 11A, 1000V HRC ones with a 20 kA breaking capacity in Fluke DMMs) come into play and use up its breaking capacity in one short bang. It's a good trick for saving money (or at least servicing costs) while maintaining safety.

Many years ago I designed a circuit for that ran off a 28V DC supply. At the supply input it had a 3.15A 20mm fuse followed by a 33R 25W  and a 33V 10W zener to qround. The aircraft supply had a 1A circuit breaker and the whole system drew about 200mA. All done and fitted. A few years later, after I'd left the company, I got a request for a "firmware" update (actully just a look-up table in PROM, no micro processor in the unit). I asked for a unit so I could check the change. I found that the unit had a 0.5A fuse fitted. On enquiry they said someone had looked at it and the 3.15A fuse would never blow so changed it. I said "go read the design and approval file" and they issued a SB to check all the units in service and change lower current fuses to the 3.25A type.
A virtual cookie to anyone who knows why the 3.15A fuse was fitted.

Protection against the 33R 25W resistor or the 33V 10W zener becoming short circuited on the incoming supply side. I'm guessing here that the I2T of the 1A breaker would mean that without the 3.25A fuse fitted, the energy let through would have destroyed your circuit. In other words you coordinated the fuse and breaker to discriminate against each other in order to allow the fuse to let go before the breaker did.

Without knowing more details it's pure speculation really.

One thing I would mention that most people seem not to know is that the primary purpose of fuses and circuit breakers is to prevent the supply wiring from heating to the point it catches fire in the event of a short.
So called fast semiconductor fuses often included to "save" expensive semis like big IGBT packs etc rarely seem to work that way; maybe that's just poor design, but back when I was mending such things a blown fuse usually indicated a blown semi-pack...

[Robert763]

Postie turned up with a package, more TE 
It's the Pico 2204A USB scope. All seems to be working at least the software finds it and it picks up mains noise when I touch the input. Got to get back to decorating though.

[Cerebus]

Without knowing more details it's pure speculation really.

One thing I would mention that most people seem not to know is that the primary purpose of fuses and circuit breakers is to prevent the supply wiring from heating to the point it catches fire in the event of a short.
So called fast semiconductor fuses often included to "save" expensive semis like big IGBT packs etc rarely seem to work that way; maybe that's just poor design, but back when I was mending such things a blown fuse usually indicated a blown semi-pack...

It's generally taken that protecting fuses with semiconductors (sic) is a sign of naïvety in the designer of anything so constructed.

[med6753]

Without knowing more details it's pure speculation really.

One thing I would mention that most people seem not to know is that the primary purpose of fuses and circuit breakers is to prevent the supply wiring from heating to the point it catches fire in the event of a short.
So called fast semiconductor fuses often included to "save" expensive semis like big IGBT packs etc rarely seem to work that way; maybe that's just poor design, but back when I was mending such things a blown fuse usually indicated a blown semi-pack...

It's generally taken that protecting fuses with semiconductors (sic) is a sign of naïvety in the designer of anything so constructed.

I contend that it's equally naive to expect fuses to protect any sand state device or component.

The 500ma fuse I installed in the Type 547 was to give a vacuum tube circuit a fighting chance in case of a short.   

[AVGresponding]

Without knowing more details it's pure speculation really.

One thing I would mention that most people seem not to know is that the primary purpose of fuses and circuit breakers is to prevent the supply wiring from heating to the point it catches fire in the event of a short.
So called fast semiconductor fuses often included to "save" expensive semis like big IGBT packs etc rarely seem to work that way; maybe that's just poor design, but back when I was mending such things a blown fuse usually indicated a blown semi-pack...

It's generally taken that protecting fuses with semiconductors (sic) is a sign of naïvety in the designer of anything so constructed.

I contend that it's equally naive to expect fuses to protect any sand state device or component.

The 500ma fuse I installed in the Type 547 was to give a vacuum tube circuit a fighting chance in case of a short.

Nevertheless it's common practice to use these to try and protect these.

The phrase "throwing good money after bad" comes to mind.

[med6753]

Without knowing more details it's pure speculation really.

One thing I would mention that most people seem not to know is that the primary purpose of fuses and circuit breakers is to prevent the supply wiring from heating to the point it catches fire in the event of a short.
So called fast semiconductor fuses often included to "save" expensive semis like big IGBT packs etc rarely seem to work that way; maybe that's just poor design, but back when I was mending such things a blown fuse usually indicated a blown semi-pack...

It's generally taken that protecting fuses with semiconductors (sic) is a sign of naïvety in the designer of anything so constructed.

I contend that it's equally naive to expect fuses to protect any sand state device or component.

The 500ma fuse I installed in the Type 547 was to give a vacuum tube circuit a fighting chance in case of a short.

Nevertheless it's common practice to use these to try and protect these.

The phrase "throwing good money after bad" comes to mind.

The fuses won't even hear the scream.

[tautech]

Mom & Pop ISP we work closely with has a new project for me. 
Please make a mount to affix it to a pole (done and shit easy) and assemble this vertical helix 200W 24V wind alternator......instructions are crap, real crap  and the B&W illustration show bugger all detail of how the 6 tiers of blades are actually fastened  so went looking for assembly videos............


8 yes 8 sequential videos how to assemble the forking thing where at a few stages it appears extra sets of hands are needed ! 
FML

[Robert763]

Mystery TEA,
Put a bid on this last night:
/www.ebay.co.uk/itm/Hightec-Instruments-Maptest-4050-Untested-/114854903985
without research, but noting the following from the photos in order of value:
A. Pelicase
B. Large Torodial mans transformer
C. Small tube furnace
D. Small pump
E. small "ticket" printer
Assumed it to be a gas analyser of some sort, but I'd pay the £9.99 just for the pelicase.
It looks like the panel frame has come unstuck, not supring when the put all the heavy bit on the front panel 
Anyway no one else bid so mine for under £19 shipped 
Did some reseach post purchase and it's a O₂ and CO₂ gas analyser.
The O₂ is a zirconia hence the tube furnace.
Even if it does not work the tube furnace will be good for hardening and tempering small tools.

[med6753]

Mom & Pop ISP we work closely with has a new project for me. 
Please make a mount to affix it to a pole (done and shit easy) and assemble this vertical helix 200W 24V wind alternator......instructions are crap, real crap  and the B&W illustration show bugger all detail of how the 6 tiers of blades are actually fastened  so went looking for assembly videos............


8 yes 8 sequential videos how to assemble the forking thing where at a few stages it appears extra sets of hands are needed ! 
FML

 

[Kosmic]

<SNIP>

I ordered something awfully similar. I'm planning to use it to make Type K thermocouple. I should also try to find some nickel strips to see how well it's working on batteries.

Edit: I did my homework before ordering and got the "Wise Maple" version that doesn't need to be fixed and should be working out of the box.

If welding thermocouples you need a carbon electrode. Using the copper or brass ones suppled with battery tab welders contaminates the alloy and can lead to inaccuracy.

I'm still not sure of the setup I'm going to use (will need to experiment a little bit), but was planning to use Nickel plated probes. If the plating is tick enough, I guess it will survive the process.