Recent Posts

1

Test Equipment / Re: Cheap oscilloscope for checking mains power quality? Also logging equipment.

« Last post by Kean on Today at 01:51:54 pm »

I don't think an oscilloscope is the best solution based on your usage.  You want a power quality analyser with data logging.  Something that can also safely be left alone.

Maybe one of these.  https://powertronics.com/collections/single-phase-power-line-monitors

See these other related discussions
https://www.eevblog.com/forum/testgear/power-line-quality-monitor-that-does-not-cost-$$$$/
https://www.eevblog.com/forum/testgear/looking-for-a-cheap-but-good-single-phase-120v-power-line-glitch-logger/

2

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by xvr on Today at 01:51:44 pm »

In LTSpice schematic you again connect all 4 pins of MOSFET to different nets. I guess that one of them directly shot some MOSFET terminal to ground. There should not be.

As for 20V - power for your amplifier should be connected to terminal that in your schematic labeled 'After relay. 24V (ar)'. I don't know what relay was connected ant where, but definitely here should be connected just plain +20V. No any +24V from any relay should be used in final schematic.

In LTSpace change voltage of V1 to +20V and remove V3

> because this floating voltage is confusing. i am used to this of voltage where each node has exact voltage with respect to some reference.

Yes, but for flying voltage will be another reference - not common ground, as for all others.
If you want to see voltage on MOSFET gate set a probe to V(Gate)-V(Souce)

3

Beginners / Re: LM324 Power Supply with variable voltage and current

« Last post by xavier60 on Today at 01:49:38 pm »

Do you mean that I need a separate winding on the transformer or another small transformer for the DVM and tap changer ?

Yes.

4

Test Equipment / Re: Fun With Low Leakage/Bias Current: Femtompere, Electrometer, Keithley 617

« Last post by BD1QMP on Today at 01:47:57 pm »

After put back the original BNC connector, I recorded the offset. Is it normal or not?  thanks

5

Beginners / Re: LM324 Power Supply with variable voltage and current

« Last post by mike_mike on Today at 01:47:07 pm »

Do you mean that I need a separate winding on the transformer or another small transformer for the DVM and tap changer ?

6

Test Equipment / Re: Siglent SSA 3021X... Ooops

« Last post by Joel_l on Today at 01:45:43 pm »

I put things back together enough to turn it on. what I found this morning was slight different that what I found ( thought I found ) last night.

Frequency is OK. I checked several points  and all were good ( Agilent E4432B )

Amplitude seems OK, worst I saw was .6 dBm low. TG trace was not horrible but I don't know what it looked like before. ( pic attached )

Input impedance is still off, the only way I have to gauge this is using one of my transmitters and TX'ing into the SA. Before the over power, I was getting a near perfect SWR, now I get high SWR on all 3 TXs I tried.

When I measure the switches, U1 is different than the others.

I went back and rechecked all the diodes in the path at each stage, all were OK.

I will replace U1 ( maybe all just cause )

Thanks

7

Test Equipment / Re: Hacking the Rigol MSO5000 series oscilloscopes

« Last post by BTO on Today at 01:45:35 pm »

I've updated the other post and there is a DETAILED PDF there............ GO FOR IT !!!
i still haven't made the video but the pdf should take care of everyone i think

8

Beginners / Re: LiPo battery charging problem

« Last post by Gyro on Today at 01:45:34 pm »

No. In fact you should use the manufacturer's utility of some other s/w to terminate the charge at around 80%. Your battery will last far longer then.

9

Test Equipment / Re: Hacking the Rigol MSO5000 - Dr Mefisto Licensing Method

« Last post by BTO on Today at 01:42:28 pm »

UPDATE : The Step by Step Instructional PDF is now available (it's detailed)

Also if possible (Because i'm interested to know) could you please leave comments if this worked for you or if it didn't , i think this will start working for everyone.

10

Repair / Re: LED Strip lights flashing like a bad 90s rave

« Last post by Grytpype on Today at 01:41:49 pm »

Thank you both for the advice. I'll check the LEDs first and carefully pick through the high-voltage side if I'm feeling brave enough.