Recent Posts

1

General Technical Chat / Re: Your pet peeve, technical or otherwise.

« Last post by Circlotron on Today at 11:22:58 am »

When your pc has 4 motherboard SATA connectors and 3 power SATA connectors. 

2

Repair / Re: ADVANTEST R9211B

« Last post by stfjohn on Today at 11:22:56 am »

How do I figure out which is pin 5 of the 63484 from the copper side of the circuit board?

3

Metrology / Re: Cost and who to adjust PM2525

« Last post by watchmaker on Today at 11:18:01 am »

It appears to be possible to calibrate this meter manually from the front panel and partially (one range at a time), and do the "cold" calibration only, pages 5-17  and 5-18 of the service manual describes the procedure. You would need an accurate source for each calibration point though or a stable adjustable source with a reference meter to get the right value. You don't need any "single trigger signals" if you do a manual calibration from the front panel. If you have a reference resistor, say 100kOhm, you could try to calibrate only 200k range and see what happens.

Cheers

Alex

Operations manual: https://doc.xdevs.com/doc/PHILIPS/PHILIPS%20PM%202525%20Operation.pdf
Service manual: https://doc.xdevs.com/doc/PHILIPS/PHILIPS%20PM%202525%20Service.pdf

My two cents is that getting this calibrated seems like a complete dead end. Even if you found a company that would do it, their price surely would be many hundreds of dollars if not close to a thousand due to the somewhat complex procedure.  You have to do both a cold and hot calibration which involves placing the unit in a temperature controlled oven, there is the proprietary connector, and part of the procedure requires opening the unit and making physical adjustments.

Even calibrating it yourself seems to be impossible since there is a page missing in the service manual and I don't see any reports of anyone successfully performing the procedure.  On top of that, this DMM has weak points, such as the battery and the motorized selector.  And it's only 21k counts (current is only 11k) with a 210k hi-res mode in some functions, with a 2,100/1,100 count high-speed mode.  And the 1A/10A input is not fused.

Thanks both.  So pro adjustment is out.

Alex, I will have to rread the manual again.  There are several SM versions out there and I do have the complete one.  But as I read it, onlu the PM 2535 has the ability to set the adjustment from the front panel while the PM2525 needs the probe or a computer to send the single trigger.

Regards

Dewey

4

Projects, Designs, and Technical Stuff / Re: An interesting 3-transistor PSU from the old USSR "Radio" magazine

« Last post by RoGeorge on Today at 11:16:27 am »

- Prisoner #439998, what was your crime? 
- I've attached LTspice pics without the .asc file.

5

Projects, Designs, and Technical Stuff / Re: An interesting 3-transistor PSU from the old USSR "Radio" magazine

« Last post by wasedadoc on Today at 11:16:19 am »

Q2 and Q3 are NOT a "constant current sink".  They pass whatever variable current is required by the load on the output up to some limit.

6

General Technical Chat / Re: Why does the US provide all critical electronic design knowledge to the world?

« Last post by radiolistener on Today at 11:11:02 am »

Every adult has the right, they choose not to, therefore they cannot complain.

The true meaning of elections is not in who gets elected, but in the act of people coming to vote. By casting their votes, they consent to being deemed incapable and relinquish control of themselves to the person appointed through the elections. The essence lies in people accepting the election results, rather than simply voting for someone.

Who you vote for does not matter. What matters is your voluntary acknowledgment of incapacity and your trust in letting those elected manage your fate.

The essence of elections is your voluntary consent to being governed by the official appointed by the elite.


Currently, there are no issues organizing voting on every matter so that each citizen of the country can make a decision. Modern technology allows this and it does not require deputies or representatives of the people. Everyone can participate in resolving all state issues themselves directly. But no one does this. Instead, the elite appoints representatives, and you must come and participate in the elections to demonstrate your consent with the appointed candidate.

7

Microcontrollers / Re: STM 32F4: any way to make it self program its FLASH from an external SPI FLASH?

« Last post by Siwastaja on Today at 11:10:34 am »

You have to assume 0x08000000 is corrupted which means any custom "boot loader" is also dead.

This sounds like a very arbitrary requirement, but sure, if you say so, then you will need a second chip. Let's not forget though that you must also assume that its 0x08000000 is corrupted too, so you will need a third chip to recover the second chip... and so on.

8

Projects, Designs, and Technical Stuff / Re: Hydrochloric Acid small volume (<=1L) NZ (Christchurch) ?

« Last post by 5U4GB on Today at 11:08:13 am »

Anyone with a swimming pool should be able to refill your bottle for you.  Or a pool service company.

Beat me to it.  Yup, try calling pool companies and say you need a tiny amount at 10% or so, you may be able to score some for free since it's usually handled in 20L or 50L carboys at a fairly respectable concentrations that could be diluted down to a larger amount.  Similarly, you could try places like Labsupply and get a tiny amount at a higher concentration, then dilute it down to the level you want.

9

Test Equipment / Re: New Brymen BM2257 Multimeter

« Last post by Fungus on Today at 11:07:28 am »

Don't know why they have the DCV adjust pot, that seems kinda dumb from a practicality point of view.

I assume they aren't calibrated. 

10

General Technical Chat / Re: Possible to trigger at battery explosions in pagers ?

« Last post by Jeroen3 on Today at 11:07:16 am »

The theory that small explosive charges were set off by a coded pager message has some major problems, in my opinion:

1) Explosives are easy to detect at airports with dogs and chemical analyzers. Why would Israeli security forces take such a big risk? The chances of one of thousands of pagers being caught over six months are just too high to gamble with.

2) If Hezbollah militants were the target, the plan simply didn’t work. Most victims only had minor burns and soft tissue injuries, with only a few fatalities reported out of thousands of pager users.

3) The explosions all happened within 10 minutes, but not at the same time. If the detonations were triggered by a coded pager message, why didn’t they go off simultaneously?

Using Occam’s razor, a simpler explanation makes more sense to me - thermal runaway of lithium batteries.

Here’s how it could have happened: the batteries had rigged BMS that caused a short circuit, and the batteries’ safety valves were probably disabled or clogged too. Also there wasn’t a trigger message - these explosions were on a timer. A variation of +/- 5 minutes over six months would approximately match the 20 ppm tolerance of a typical 32,768 Hz crystal. And the goal wasn’t to target users but to disrupt enemy communications by destroying their devices (pagers and later radios).

1) are cargo pallets scanned that thoroughly as well?
2) it did work, it put heavy load on services and exposed lack of trust in supply chain that needs addressing. Plus it disrupted communications for some time. Maybe even days.
3) Here in NL we have a cell broadcast emergency messages and these do not all trigger at the same time. Sometimes minutes later.

I would assume pagers get network time?