What did you buy today? Post your latest purchase!

[gamalot]

Agilent 4338B Milliohmmeter. 

[PlainName]

Nice, but not going to fit in a rack if all those clip-on wires are needed to make it work. At least, not unless it's the top item.

[gamalot]

Nice, but not going to fit in a rack if all those clip-on wires are needed to make it work. At least, not unless it's the top item.

I couldn't find the software for calibrating via GPIB, so I opened it up and planned to do some reverse engineering by logging the EEPROM accesses.

[PlainName]

Good luck 

[thm_w]

Agilent 4338B Milliohmmeter. 

Hotwheels lol
For anyone else wondering the resolution is 10μ\$\Omega\$

[gamalot]

Agilent 4338B Milliohmmeter. 

Hotwheels lol
For anyone else wondering the resolution is 10μ\$\Omega\$

My son believes the Hotwheels stickers he gave me will make my equipments work better. 

[DiTBho]

Bought qty=4 Brymen BM857 multi-meters and one optical link cable. I got -20% off, free bags and free shipping.

Arrived yesterday, looks the best deal ever

Three units are for my friends, one multi-meter is for me.

I know there is Sigrok support, but I am going to write my own application for Linux.

The serial communication is not complex, I have already downloaded the documentation about the protocol, and it's all textual presentation of measurement values, floating point, normalized mantissa plus exponent, combined with binary bit fields for current meter's function and measured unit.

So, kind of variable length records with control chars in the header and footer around the mode flags and value's text, and up to 22 bytes per serial packet.

[rsjsouza]

You and your friends will love the BM857 - it is a great meter!

[GreyWoolfe]

Scored a crazy deal on bamboo flooring for office/lab.  Paid $1.40 a square foot for what Home Depot sells for $3.49.  No more crappy concrete floor. 

[rsjsouza]

Just be absolutely sure to watch for the moisture on the floor if you are installing it directly in the concrete foundation. In our previous house we suffered with infiltration from the concrete slab that not only ruined the floor after some 10 years but also added a lot of mold to our house. If you have a basement, then it shouldn't be a problem.

[Ed.Kloonk]

Plastic down first. Stitch it together with duct tape/gaffer tape. Make it like a bath tub.

You should also consider a foam underlay (2-3mm thick?).

 

[gamalot]

Marconi 2024 9kHz-2.4GHz signal generator, arrived this morning, fixed in 30mins by replaced a capacitor in the power supply. I have to do some cleaning later

After about 6 years, this unit failed again! There is no response after pressing the power button, it seems that the SMPS is broken again.

I opened the case and measured and all the rails had no output, so I took the power module out to check and didn't see or smell anything wrong. However, just when I tried to flip it over in order to inspect the bottom side of the PCB, I was shocked badly. 

My ring finger hurts so much! Yes I know that the capacitor must be discharged before repairing the switching mode power supply, but I clearly saw that there are two discharge resistors on the PCB, and this electric shock should not happen! I checked the 4 capacitors (2S2P) next to the rectifier bridge with a multimeter, two of them measured 250V and the other two measured 0V, so I found a suitable resistor to discharge those two dangerous capacitors.

Then I removed the two discharge resistors from the PCB for measurement. One of the resistance values ​​was a normal 100K, and the other was measured as an open circuit.

I found two 150K resistors, they are a bit big in size, but still fit into place on the PCB, after soldering them I put the power module back in the case, connect all the cables, press the power switch down, and it works!

[PA0PBZ]

I found two 150K resistors, they are a bit big in size, but still fit into place on the PCB, after soldering them I put the power module back in the case, connect all the cables, press the power switch down, and it works!

Are you now suggesting that replacing the discharge resistors fixed it? That should not happen... 

[gamalot]

I found two 150K resistors, they are a bit big in size, but still fit into place on the PCB, after soldering them I put the power module back in the case, connect all the cables, press the power switch down, and it works!

Are you now suggesting that replacing the discharge resistors fixed it? That should not happen... 

This is also where I am confused, the only explanation I can think of is that the two discharge resistors are also used to prevent uneven voltage drops across the two electrolytic capacitors in series.

[shakalnokturn]

Are you now suggesting that replacing the discharge resistors fixed it? That should not happen... 

I have one PSU design in mind where one of the two bleeder resistors doubles as startup power supply to the PWM.

[tautech]

Are you now suggesting that replacing the discharge resistors fixed it? That should not happen... 

I have one PSU design in mind where one of the two bleeder resistors doubles as startup power supply to the PWM.

Yep by far the safest implementation in SMPS is for the controller to continue running until the charge in the HV caps are depleted to safe levels where under voltage lockout engages and stops operation in a safe state.

[BU508A]

Arrival today:

- 3x Huber & Suhner RG58 BNC cables, 2m each
- 4 pairs of MultiContact (Stäubli) Cu-Be 4mm hollow banana plugs
- 2 TRACO THL 15-2412WI DC-DC converter (9-36V in, 12V out, max. current 1250mA)

[shakalnokturn]

A seriously cute Philips PM2424 autorange Nixie DMM.
It's about my age. I may actually use this one if I can tame the whistling that comes from the PSU.

[mansaxel]

Plastic down first. Stitch it together with duct tape/gaffer tape. Make it like a bath tub.

You should also consider a foam underlay (2-3mm thick?).

 

Here in Sweden, the building code says that the slab shall be free of capillary humidity transmission from the ground; so under the cast concrete there shall be a layer of coarse gravel without sand, or an insulating layer of expanded cell foam or both. The slab shall be dry in all circumstances. Then, inside the insulation, so there is no condensation-triggering  temperature gradient, a special aging resistant plastic film is required, with its accompanying tape. Very sticky.  Done right, with enough ventilation, it's nearly foolproof.  A challenge is to keep enough ventilation in these constructions, since there is a tendency to minimise draught for energy efficiency reasons. (we're on 60° North, so it gets cold in winter.)  I rather freeze than get sick from mold spores.

[Ed.Kloonk]

Plastic down first. Stitch it together with duct tape/gaffer tape. Make it like a bath tub.

You should also consider a foam underlay (2-3mm thick?).

 

Here in Sweden, the building code says that the slab shall be free of capillary humidity transmission from the ground; so under the cast concrete there shall be a layer of coarse gravel without sand, or an insulating layer of expanded cell foam or both. The slab shall be dry in all circumstances. Then, inside the insulation, so there is no condensation-triggering  temperature gradient, a special aging resistant plastic film is required, with its accompanying tape. Very sticky.  Done right, with enough ventilation, it's nearly foolproof.  A challenge is to keep enough ventilation in these constructions, since there is a tendency to minimise draught for energy efficiency reasons. (we're on 60° North, so it gets cold in winter.)  I rather freeze than get sick from mold spores.

What happens here is the home owner often builds up dirt outside for garden beds, sometimes even higher than the inside floor level. Where I am we've had a stupid amount of continuous rain and the rising damp is causing all sorts of problems whereas in, I dunno, 4 years of extreme drought it hasn't mattered.

[Nominal Animal]

Here in Sweden, the building code says that the slab shall be free of capillary humidity transmission from the ground

Very similar in Finland, of course.  Mom's house is at 68°N, with the bottom floor underground, and never had any issues with the slab – actually, both the floor and the walls of the bottom/underground floor are concrete.  Granted, there is very little soil, and the ground is sand with layers of gravel, with a few meter permafrost layer starting at about 3m depth, and very pure groundwater (filtered through all that sand!) at about 15m deep.  Construction-wise it has double-width (100mm) expanded foam (EPS, brand name styrox) all around, and as a trick to deal with meltwater, underground "fins" of expanded foam sloping outwards at about 1m ground depth, to about 2m out from the house.  There are also underground drainpipes all around the house, of course, leading outwards.  40 years later, still zero mold issues, and the amount of meltwater each year easily compares to a flood.  Erosion in home road is a problem; that does needs fixing every few years.

I can imagine how difficult it is to achieve the same with a thicker soild and/or clay-based ground.

[porter]

HunterBee 10X Built-in LED Lighted Optical Glass Magnifier
$16.99 from amazon.

[rfclown]

Two LM3909s. The day after I ordered them, I realized I might have one in something I built many years ago. Digging in the garage I found the oldest one in the photo, the other two were "pulls". I hadn't soldered mine into the circuit I had built, just wrapped wires around the leads. I now have one of each logo.

[xrunner]

HunterBee 10X Built-in LED Lighted Optical Glass Magnifier
$16.99 from amazon.

Oh cool - just ordered one from AMZ. 

[Alex Eisenhut]

https://www.ebay.ca/itm/113223858857

It's like finding an original in-box part for a 1967 Chevy. Pretty cool if you roll that way. This kit is to replace a rare GaAs switching diode (not tunnel).

Will be added to my collection of original Tektronix baubles.