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Type: Posts; User: KlausST

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1. ## Thread: Battery cutoff voltage vs 0% battery voltage

by KlausST
Replies
4
Views
140

### Closed: Re: Battery cutoff voltage vs 0% battery voltage

Hi,

Cutoff voltage depends on battery, not on application.
For sure you may measure the battery voltage...but it gives not much information about health and charge...
2. ## Thread: Wiring of DC fans in Series

by KlausST
Replies
12
Views
219

### Closed: Re: Wiring of DC fans in Series

Hi

Try this:
* NPN, PNP, 2x R = 4k7

Wire it this way:
* 30V --> NPN_C
* NPN_E to PNP_E = 15V output
* PNP_C to GND
* resistors in series, one end to 30V, the other end to GND.
3. ## Thread: Holding button for 2s to trigger 555 timer

by KlausST
Replies
2
Views
102

### Closed: Re: Holding button for 2s to trigger 555 timer

Hi,

On button press: the capacitor gets slowly discharged by a high ohmic resistor
On button released: the capacitor fastly gets discharged via a diode

Klaus

by KlausST
Replies
32
Views
1,348

### Closed: Re: 12 Bit ADC with interfacing SPI in STM32

Hi,

that's the wrong way round

Klaus
5. ## Thread: At45db041b vs at45d041

by KlausST
Replies
2
Views
81

### Closed: Re: At45db041b vs at45d041

Hi,

If I need to know that, I'd compare the datasheets.

I'd focus on voltage levels, timing...

Klaus
6. ## Thread: L293d - Input Voltage (motor operation)

by KlausST
Replies
1
Views
72

### Closed: Re: L293d - Input Voltage (motor operation)

Hi,

You should not guess, better read the datasheet.
It clearly says every input voltage above 2.3V is valid HIGH level.

Better than long textual description is a picture.
7. ## Thread: Wiring of DC fans in Series

by KlausST
Replies
12
Views
219

### Closed: Re: Wiring of DC fans in Series

Hi,

A power voltage divider could be made with two equal resistors, an NPN and a PNP...
Not very precise, but good enough for fans

Klaus

by KlausST
Replies
32
Views
1,348

### Closed: Re: 12 Bit ADC with interfacing SPI in STM32

Hi,

Your scope picture (especially the upper one of post#29) is awful. Don't you recognize that the sampling rate is much too low for your signals. The SCK looks far away from being a square wave....
9. ## Thread: Generation of 4 Phase Shifted clock Signals

by KlausST
Replies
5
Views
182

### Closed: Re: Generation of 4 Phase Shifted clock Signals

Hi,

From your first post I thought about sinusoidal waveform with positive and negative voltage swing.

Now it seems to be a squarewave...
with unknown voltage swing.
Unknown risetime and...
10. ## Thread: USB to RS232 exactly similar to COM1

by KlausST
Replies
9
Views
264

### Closed: Re: USB to RS232 exactly similar to COM1

Hi,

draw a sketch.

Klaus
11. ## Thread: Battery cutoff voltage vs 0% battery voltage

by KlausST
Replies
4
Views
140

### Closed: Re: Battery cutoff voltage vs 0% battery voltage

Hi,

it (solely) depends on the battery.
Read the battery datasheet or contact the manufacturer.

Also visit www.batteryuniversity.com

Klaus

by KlausST
Replies
5
Views
191

### Closed: Re: Using AD831 in parallel

Hi,

I doubt the PCB is getting hot. Usually the electronic parts getting hot. .. and only some of them.

To detect which one is getting hot:
* power off and let all get down to room...
13. ## Thread: USB to RS232 exactly similar to COM1

by KlausST
Replies
9
Views
264

### Closed: Re: USB to RS232 exactly similar to COM1

Hi,

No.
It just says it works with your computer, but it does not say anything about compliance.
*****
True: RS232 idle state = high = 1 = negative voltage (lower than -5V)
*****
...It...

by KlausST
Replies
5
Views
191

### Closed: Re: Using AD831 in parallel

Hi,

First you need to determine:
* How much current can your supply deliver
* How much current do you expect your circuit to draw
* Measure how much your circuit really draws

We don't know...

by KlausST
Replies
3
Views
154

### Closed: Re: Maintaining supply voltage on load

Hi,

There is no GND plane? Is it?
(Maybe you used copper pour --> this is not compareable to a GND plane)

If not: good luck.
Especially with your switching power application.
Did you test:...

by KlausST
Replies
5
Views
191

### Closed: Re: Using AD831 in parallel

Hi,

* too high current

Klaus

by KlausST
Replies
32
Views
1,348

### Closed: Re: 12 Bit ADC with interfacing SPI in STM32

Hi,

1k seems to be OK.

But in detail it depends in:
* expected speed
* drive strength of the output pin
* signal trace length, connected devices (= capacitance)

The good thing is:
18. ## Thread: average value of as square wave

by KlausST
Replies
6
Views
184

### Closed: Re: average value of as square wave

Hi,

What "design procedure" ? ...for two parts: R, C.

R C low pass filters are explained million times in the internet, since it's probably the most used circuit.

Klaus
19. ## Thread: average value of as square wave

by KlausST
Replies
6
Views
184

### Closed: Re: average value of as square wave

Hi,

A low pass filter?

Klaus
20. ## Thread: How to calculate transformer winding losses

by KlausST
Replies
4
Views
166

### Closed: Re: How to calculate transformer winding losses

Hi,

To be honest: I donīt know the answer.

* maybe the copper loss is tested with DC. Then there are additional losses caused by AC: Proximity effect and skin effect.

***
21. ## Thread: USB to RS232 exactly similar to COM1

by KlausST
Replies
9
Views
264

### Closed: Re: USB to RS232 exactly similar to COM1

Hi,

There is no need for 11V. If Im not mistaken, then even 3V / -3V levels comply with RS232.

If your connected hardware does not work with levels below 11V, then...
22. ## Thread: power supply residual voltage

by KlausST
Replies
6
Views
188

### Closed: Re: power supply residual voltage

Hi,

I donīt think this is possible.
Most probably the power has a a capacitor at the ouput.
It needs a lot of power to charge this capacitor to +/-12v within 10us.

And negative voltages...

by KlausST
Replies
2
Views
91

### Closed: Re: ADC input with low pass RC filter

Hi,

We donīt know what kind of ADC you try to build.
We donīt know what cutoff frequency you like to have.

No.
If you solve the above equation with...
24. ## Thread: Desperate for help (computer fan control) or this could cost huge \$\$\$

by KlausST
Replies
7
Views
374

### Closed: Re: Desperate for help (computer fan control) or this could cost huge \$\$\$

Hi,

Did you read the WIKIPEDA article.

It says it delivers 2 pulses per revolution.
That's all you need.
Measure/calculate the count of pulses per minute and divide it by 2 ... and you are...

by KlausST
Replies
3
Views
248

Hi,