Recent Posts

1

Test Equipment / Re: SDS800X HD Feature/Improvment disscusions

« Last post by ebastler on Today at 01:50:43 pm »

Still i dont know how i should capture that last falling edge, since i cant not move the gate there, wenn i want to measure both delays at the same time.

But why do you still need the gate cursors at all now?

With the fast PWM pulses gone, you can now measure the time between any CH1 falling edge and the next CH4 rising edge which follows that, right? And likewise for the other timing measurements you want to take in parallel. I think you can just disable the gating function entirely.

2

General Technical Chat / Need 13Amp variac device to 'modulate' a water boiler.

« Last post by paulca on Today at 01:45:56 pm »

I have previously been using a cheap Chinese variac(?) PCB claiming 40A (lol).  However, after the wire clamps melted and I soldered them on instead, I still don't trust it. I decided I want to upgrade it to be far less janky.

Has anyone seen a reasonably priced high power dimmer?

I'm okay with AliExpress et. al.  As long as there is evidence the thing won't melt at 13Amps for an hour doing a boil and will tolerate another hour at 30% output without melting.

My next home brew beer is depending on this!  Help me make beer!

3

Projects, Designs, and Technical Stuff / Re: I think I need a little help. AC IN switch circuit.

« Last post by MarkF on Today at 01:45:18 pm »

Here is a picture that may help in understanding my dilemma. The main PCB covers the entire area inside the box and I really don't want AC running around or over the other circuits.

That's why they make these:



Route your wires along the frame away from sensitive components and tie them in place with self-stick mounting pads.

4

General Technical Chat / Re: Proof that software as service/cloud based, will never work for long term ...

« Last post by paulca on Today at 01:41:03 pm »

The AWS, Azure, Blue Ocean et. al. lock in is very real.

I found out to my confusion recently that the UK government is single vendor locked now.  To Azure.

As far as my historical understanding of government IT ... it should NEVER be single vendor.

5

Projects, Designs, and Technical Stuff / Cannibalising a minidisc for parts for a automaton

« Last post by banjobill on Today at 01:37:05 pm »

Hi, I'm new to the forum and new to electronics so apologies if I ask dumb questions.

I have an old Sharp Minidisc and before binning it I looked for anything I could re-use - I'm interested in making automatons.  There is a tiny motor and worm gear that positions the laser read/write head which looks like it could be useful.

Any suggestions on how to decode where power should be applied, how much, tracking down datasheets (next to no part numbers).  Or am I wasting my time?

Cheers

6

Test Equipment / Re: Looking for a replacement general purpose oscilloscope for home use

« Last post by joeqsmith on Today at 01:36:36 pm »

Sounds like it may need a new screen but the one picture they show, I didn't notice the defects seller mentions.  Even without any options,  that was a deal, assuming it has no other problems. 

I bought a DMM from a large distributor people use here.  When it arrived, it was pretty obvious some wannabe reviewer had taken it apart and in the process had damaged a cable and lost a screw, then returned it.   

7

Repair / Re: Heathkit EC-1 Analog Computer repair

« Last post by wasedadoc on Today at 01:33:02 pm »

As I see from cct diag  posted,, it has only two operational amplifiers.
So, it will be capable of solving some 1st order ODE, and  a basic  2nd order  ODE.

No.  Only two opamps (1 and 9) are drawn in full.  The others are repeats.  See the text "AMPLIFIERS 2ND THROUGH 8TH"

8

Test Equipment / Re: Looking for a replacement general purpose oscilloscope for home use

« Last post by Kosmic on Today at 01:26:13 pm »

...
I hope he had some kind of refund from the seller. Finding a replacement motherboard (with pcie/104 and LVDS onboard) is not going to be easy nor cheap.

If I were the seller and saw someone pulling my equipment apart like this with total disregard to basic ESD practices, I would not only reject any claims, but most likely would make a video rant about wannabes.     

I was assuming he came to a closure with the seller before digging in. But ... maybe not 

Imagine the reaction of the seller when he receive the returned scope in parts. And the worst is that I'm sure Ebay would side with the buyer.

A similar scope sold for 1675$ 2 days ago on ebay https://www.ebay.com/itm/235512623988. I was expecting a lot higher.

9

Test Equipment / reading Keysight 3458A serial number

« Last post by analogRF on Today at 01:25:24 pm »

I have a 3458A with the S/N sticker missing.
The firmware revision is 9.2
Is there any way I can read the serial number of the instrument?

ID? only says HP3458A and obviously it does not understand SCPI language

10

Beginners / Re: Op-amp peak detector doesn't match the peak input

« Last post by icecats on Today at 01:20:36 pm »

Maybe test the circuit with an input from a battery (known voltage source).

Just to confirm the issue still exists.  That will rule out the possibility that there's actually more voltage on your input signal than you can see on the scope. Like maybe it's too short for the scope to see but not the opamp, or maybe the scope is loading the signal and you never see it with scope connected etc..  a battery is a known DC voltage, so you can rule out stuff higher voltages you cant see.

Good suggestion! I put together a voltage divider to output 2v (so as to be well below the V+ supply) and connected it to the op-amp input. Indeed, the op-amp output reads 2v as expected.