Recent Posts

1

General Technical Chat / Re: Does anyone make good SSDs any more?

« Last post by Infraviolet on Today at 04:07:37 am »

The samsung 870 EVO is still a particular model to really avoid then? Or are things better with more recently manufactured ones?

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Buy/Sell/Wanted / Re: SALE (AU/NZ): Multicomp Pro MP710086 (Owon P4305 rebadge) at element14

« Last post by plurn on Today at 03:46:55 am »

Ok this is just getting ridiculous. They are practically giving them away. AU$62.09 (AU$68.30 inc gst). AU$61.47 with 10% discount.

I ordered another 2 at this price. Note if you get the one with order number 3227419 then since it does not have an "01" or an "02" at the end it is not considered discounted - so you can apply the 10% discount (I was not able to apply the 15% off one - maybe because I have already used it once - worth a try though). It is weird that they reduced the price on the main order number rather than just on the "02".

There is a bunch of other stuff that was further reduced in price today. So worth searching through their stock for items located in Australia. Some other bargain items I found:

cheap multicore solder - various types <AU$21 for 250g
CT-ISO1L Isopropanol 1l ~AU$9
KNIPEX 82 02 200 twingrip pliers ~AU$32
KNIPEX 87 01 125   cobra 125mm ~AU$26
various knipex super knips (electronics flush cutters) for <AU$30
various ender-3 3d printers for <AU$130 - usually over $300. Was tempted by this but not sure how much I would use a 3d printer.

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Test Equipment / Re: Siglent SDS800X HD 12 bit DSO's

« Last post by ballsystemlord on Today at 03:44:42 am »

Well, no.  They specifically tell you there is no internal 50 ohm termination and that you have to use an adapter.  No deception here.

I meant that if the input impedance is 1Mohm, then specifying 50ohm impedance was possibly deceptive as that doesn't reflect the reality of the scope's input.

Thanks for the explanation. I understand now.

4

Repair / Re: Blaupunkt CR-4096 AM/FM/Cassette playing speed too fast

« Last post by floobydust on Today at 03:32:23 am »

OP, you know the little circuit board the motor connects to, is the speed controller. I don't see a tachogen for feedback so it must be motor back-EMF?
The board has a trimpot to adjust motor speed. But if yours is way fast then the power transistor could have shorted.

How I used to calibrate speed, is record a test tone say 10kHz on a cassette deck that I know has correct speed, musicians can tell right away if pitch is off.
Then put the cassette in the deck and adjust speed until a freq. counter reads correctly.

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Projects, Designs, and Technical Stuff / Re: Vacuum Fluorescent Display Driver

« Last post by floobydust on Today at 03:27:31 am »

Do confirm there is enough room (height) available as I believe it has to fit underneath the display.

6

Repair / Re: Please help, how can I adjust this transistor?

« Last post by daisizhou on Today at 03:22:20 am »

Thanks

I checked Q3, Q4, Q5, Q6, and I found that their pin resistance is very small, only about 130 ohms。I measured it online, so it may not be very accurate.but very strange.

The resistance values of Q28 and Q29 are also very small. I am still looking for the pin location. The resistance value is only about 40 ohms.

Give me some time and I will test them all and mark the pin locations and suspected resistance values.

7

Repair / plug in power meter flaw

« Last post by daniel444 on Today at 03:22:16 am »

my plug in power meter just died ,  a few years earlier it had stopped working so i opened it up and found the built in battery leaking , so i cut the battery out and cleaned the electrolyte off the board.
this caused it to work again for a few years , now it has stopped working again , the electrolyte had soaked into the board beyond my ability to clean it off , and its beyond my ability to repair.

if your going to buy one of these power meters  remove the built in battery immediately

8

Beginners / Re: AC to split supply

« Last post by jwet on Today at 03:22:11 am »

I saw that you got no replies so I'll wade in...

You want to go from 240VAC line to +5 and 1.5A and -5 at 1.5A  plus 3.3 at 20 mA.

First, the 3.3 20 mA requirement will just be a linear from the +5v rail.  LM1117, etc.

If the + 5v and - 5v rails, are truly balanced, this is pretty simple?  (Usually +5v is loaded more than -5v.)  If they truly are loaded equally, you could use a 4.5 VAC output transformer- this will give you about 6v DC after half wave rectifier and filter.  Rectify one wire from transformer to make a bipolar supply.  Use a forward diode and big cap and a reverse diode with big cap and tie the other side of transformer to other side of secondary output- this will be common.  You'll have a +-6v supply.  Add your favorite pos and neg linear regulators and the then the little 3.3v linear.

If the +5 and -5 are not substantially equal, it gets more complex.

Below is a pic that I found online from EE Stack Exchange that should get the idea across, details will be different for your voltages, etc

Good Luck

9

Microcontrollers / Re: Identify MCU

« Last post by mon2 on Today at 03:20:26 am »

The msop10 packaged device is a PLL with m5351A (clone of the si5351a). Datasheet of the clone is on lcsc.com.

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Buy/Sell/Wanted / Re: Element 14 Australia Fire Sale

« Last post by aeberbach on Today at 03:20:15 am »

14 now