Recent Posts

1

Beginners / Re: Transformer - Mains Oscilloscope Probing

« Last post by Silenos on Today at 10:44:00 am »

then the RCDs of the neighboring houses will be triggered

Ewww how on earth you come up with such an idea? That's why everyone has their ows sets of RCD and fuses...
Ok, let me put it straight. You never have to hack the installation in osciliscope cases, ever. And the type does not matter, either. I was just explaining you what will happen when you connect neutral with PE, and I still have no idea why you insist on doing that except the evervague "safety reasons" - it is a mistake in any case, that's all.

At least in my part of Europe neutral wire is considered "high voltage" (230/400 V) wire in the safety standards, and it is supposed to be treated like this. And in a real installation there is always some N-PE voltage floating due to return currents, hence the RCD action when connecting these wires.

Disclaimer: you would be surprised what can the PE in wall socket be connected to, especially in older households, sites, with TN-C 2-wired installations. Though no idea of such "traditions" in your area.
Ok, cut this subject, just don't mess with it.

So now some board is appearing. No idea what exactly are you going to measure. What do you mean "right values"? Measuring anything with the osciliscope will always show "false values", as you are biasing the DUT with a probe. The transformer is also a machine collapsible to iirc simple RLC/magnetic flux circuit.

2

Beginners / Re: Mobile Stepper Motor Driver Project / Use of membrane buttons

« Last post by m k on Today at 10:43:43 am »

Has anyone had a custom membrane keypad made?

More like Projects and Designs stuff.

Click report and request moderators a change.

3

Beginners / Re: Bush tv LT26MC1A with a 715T2907-2 psu

« Last post by m k on Today at 10:42:01 am »

What is main filter cap, C920?

IC901 pin8 must have Vcc, it's from T901 feedback winding.

What IC902 pin2 has?

4

Projects, Designs, and Technical Stuff / Re: Thermocouple probe temperature range

« Last post by perieanuo on Today at 10:40:20 am »

Hi, in similar case I used threaded M3 thermocouple screwed into aluminum heating plate (well, 2 cylinder heating resistors were used to heat the plate). Just position your thermocouple in a good position.
If you wanna do it with your choice, use a wire terminal, those used with M3/M4 screws by pressing your thermocouple ending gently into the terminal, this will do too if you choose correctly his mounting spot and the force to keep it in the terminal at minimum needed.
https://www.tme.eu/ro/details/1-320551-3/terminale-izolate/te-connectivity/

5

Beginners / Re: Help with modeling CdS cell in LTspice

« Last post by Zero999 on Today at 10:40:13 am »

I wouldn't bother with trying to simulat the light or anything. Just use a voltage controlled resistor.

6

Projects, Designs, and Technical Stuff / Re: Can't make sense of this circuit on a controller loop

« Last post by Cuchi on Today at 10:29:02 am »

Hello,

I am a new member of this site and a beginner in the subject. I don't know how to navigate it yet but I came across your post while doing a search and I'm telling you my problem thinking that you might be able to help me find the solution or tell me where to ask my question more effectively


I purchased a controller as specified below

an PWM type single channel H-Bridge DC brushed motor driver for automotive use
The pin assignment is as follow:

an Output high-side current monitoring function (OCM pin):+VIN; GND and M+;M-

A Microcontroller(inputs):
PWM1: Driver control signal input pin 1
PWM2: Driver control signal input pin 2
EN
GBD
+12V OUT

I plan to use it to vary the speed of a 12 volt electric motor (a motorcycle starter) connected to a 12 volt motorcycle battery as well.
The problem is that when I connect the throttle to the controller inputs (+12v pin; Gnd pin and signal pin) the output signal of the throttle connected to the PWM1 input of the controller, I obtain an inverted effect, i.e. the motor spins when the throttle is closed and at rest and the motor stops when the throttle is opened with the lever pushed all the way. If I connect the throttle signal pin to the PWM2 of the controller nothing happens

My question is how to reverse things, i.e. make the motor spin as the throttle is applied towards more gas and not the other way around.
Thanks

7

Microcontrollers / Re: CH32V003 : Howto use PWM and driving Sg90 Servo Motors

« Last post by Cuchi on Today at 10:24:13 am »

Hello,

I am a new member of this site and a beginner in the subject. I don't know how to navigate it yet but I came across your post while doing a search and I'm telling you my problem thinking that you might be able to help me find the solution or tell me where to ask my question more effectively


I purchased a controller as specified below

an PWM type single channel H-Bridge DC brushed motor driver for automotive use
The pin assignment is as follow:

an Output high-side current monitoring function (OCM pin):+VIN; GND and M+;M-

A Microcontroller(inputs):
PWM1: Driver control signal input pin 1
PWM2: Driver control signal input pin 2
EN
GBD
+12V OUT

I plan to use it to vary the speed of a 12 volt electric motor (a motorcycle starter) connected to a 12 volt motorcycle battery as well.
The problem is that when I connect the throttle to the controller inputs (+12v pin; Gnd pin and signal pin) the output signal of the throttle connected to the PWM1 input of the controller, I obtain an inverted effect, i.e. the motor spins when the throttle is closed and at rest and the motor stops when the throttle is opened with the lever pushed all the way. If I connect the throttle signal pin to the PWM2 of the controller nothing happens

My question is how to reverse things, i.e. make the motor spin as the throttle is applied towards more gas and not the other way around.
Thanks

8

General Technical Chat / Re: Dumpster diving save VFD

« Last post by AVGresponding on Today at 10:24:10 am »

I bought a pack of thin (maybe 0.8 to 1 mm) plastic sheets on Amazon, various colors. I think they called them acrylic but they were more flexible like polycarbonate. Used some for contrast filters on CRT oscilloscope, as well as VFD displays. My favorite color is "rose", kind of pale pink. It makes the VFD look white, by filtering out some blue and green. Can be combined with smoke for additional contrast. I've also used colored "gel" or cello or cellophane sheets, which are very thin. This needs to go in between the VFD glass and some other durable lens like acrylic.

Yeah, gel sheets are good, though you do need to combine them with a rigid sheet of something. They are available in a large range of colours too

9

General Technical Chat / Re: Where'd Mornsun go?

« Last post by S. Petrukhin on Today at 10:10:06 am »

The sanctions obviously prohibit not selling only, but transferring money for what is sold.

Probably, the stocks were taken and successfully sold from us. Mornsun has very good sales in Russia, as far as I know.

10

RF, Microwave, Ham Radio / Passive RF SP12T Switch? Does it exist? Is there a better way?

« Last post by tbw2 on Today at 10:09:37 am »

How could I select between a dozen 5MHz@400Vpk-pk signals, passively, whilst maintaining good isolation, and 50Ohm Characteristic impedance?

Currently I have a "cat of nine tails" cable which is slow and fragile.

I am imagining a rotary switch with 12 poles, but cannot find a 50Ohm characteristic impedance version. Do they even exist?

What other solutions are out there?

Thank you in advance.