Search found 1594 matches

by dyarker
Fri Jun 18, 2021 1:14 am
Forum: General Discussion
Topic: How does a voltage divider circuit to run an LED?
Replies: 6
Views: 429

Re: How does a voltage divider circuit to run an LED?

Five 1K resistors in series with the LED should work. The wattage will be divided across the 1/4W resistors, so will be less than 1/4W on each. If not bright enough, go to four resistors. Will need color of LED for closer calculations. Cheers, (late add - be careful of polarity of LED. If you put it...
by dyarker
Thu Jun 17, 2021 12:23 am
Forum: General Discussion
Topic: How does a voltage divider circuit to run an LED?
Replies: 6
Views: 429

Re: How does a voltage divider circuit to run an LED?

If he was using 62VAC, the LED would be destroyed immediately unless also including a standard rectifier diode in series.
by dyarker
Mon Jun 07, 2021 3:19 am
Forum: General Discussion
Topic: How does a voltage divider circuit to run an LED?
Replies: 6
Views: 429

Re: How does a voltage divider circuit to run an LED?

A "regular" indicator LED is commonly 20mA maximum. Design for about 17mA. The forward drop of an LED depends on color. 1.8V for red, to 3.8V blue, other colors in between. Suggest you calculate 62V for 19mA through LED. That leaves a margin for a little over 62V, and 54V long term safe. If that it ...
by dyarker
Sun Apr 11, 2021 5:07 am
Forum: Computer Programming
Topic: 74HC595A Shift Register Outputs Low Level?
Replies: 3
Views: 522

Re: 74HC595A Shift Register Outputs Low Level?

4 days. It was output enable?
by dyarker
Sat Apr 10, 2021 9:54 pm
Forum: General Discussion
Topic: Crappy Headphone wires.......
Replies: 11
Views: 3315

Re: Crappy Headphone wires.......

CAT-5 or CAT-6 patch cords are of stranded wire.
by dyarker
Wed Apr 07, 2021 8:21 am
Forum: Computer Programming
Topic: 74HC595A Shift Register Outputs Low Level?
Replies: 3
Views: 522

Re: 74HC595A Shift Register Outputs Low Level?

You need a better spec sheet, like - https://www.onsemi.com/pdf/datasheet/mc74hc595a-d.pdf (not from TI, but is for the "A" part (74HC585 A )) Also needed - A schematic diagram of your circuit. My first EWAG based on limited info provided is OUTPUT ENABLE pin needs to be pulled up. side comment - Th...
by dyarker
Tue Mar 23, 2021 5:38 pm
Forum: General Discussion
Topic: 555 Timer ic question please
Replies: 9
Views: 630

Re: 555 Timer ic question please

agreed!
by dyarker
Mon Mar 22, 2021 11:10 pm
Forum: General Discussion
Topic: 555 Timer ic question please
Replies: 9
Views: 630

Re: 555 Timer ic question please

I asked "Do you want re-triggerable?" He answered "Yes". Which is wrong based on rest of answer. "Re-trigger" does not ignore triggers during time period. You said the "yes" was to the "Ignore"; but that was not the question! Please learn to READ before butting in! Back to post 1 - regardless of if ...
by dyarker
Mon Mar 22, 2021 5:59 pm
Forum: General Discussion
Topic: 555 Timer ic question please
Replies: 9
Views: 630

Re: 555 Timer ic question please

additional triggers do not exceed the Delay Time Then the answer is NO. You want additional triggers during the delay ignored till after the delay, Then another trigger starts a new delay. "Re-trigger" means the output could stay on forever, as long as triggers happen before the delay time since th...
by dyarker
Mon Mar 22, 2021 9:21 am
Forum: General Discussion
Topic: 555 Timer ic question please
Replies: 9
Views: 630

Re: 555 Timer ic question please

It can be either way. Re-triggerable takes a couple transistors; one to discharge the timing capacitor to start the time over again.

Do you want re-triggerable?

Cheers,
by dyarker
Thu Mar 18, 2021 8:21 pm
Forum: General Discussion
Topic: Adafruit 1.2" led display
Replies: 11
Views: 1101

Re: Adafruit 1.2" led display

Haklesup, It says that it has been discontinued.
How would he know? Requires reading.
by dyarker
Mon Mar 01, 2021 8:19 pm
Forum: General Discussion
Topic: 555 timer missing pin
Replies: 4
Views: 574

Re: 555 timer missing pin

Pin 6 would be the pin for the connection missing a pin number.

Pin 5 is also not shown, but is the junction of internal voltage divider, so does not need to be used in this case.

Cheers,
by dyarker
Mon Nov 02, 2020 8:34 pm
Forum: General Discussion
Topic: Power Supply for mains circuit _linear or switch mode
Replies: 7
Views: 1515

Re: Power Supply for mains circuit _linear or switch mode

The load is 15 ohms at 120 Volts and 12 amps DC.
Does not compute!

120V / 12A = 10 Ohms

Or, if the 15 Ohms is correct, then 12Amps is wrong; like JWax said.
by dyarker
Mon Nov 02, 2020 2:13 pm
Forum: General Discussion
Topic: Power Supply for mains circuit _linear or switch mode
Replies: 7
Views: 1515

Re: Power Supply for mains circuit _linear or switch mode

I have never of anything needing 110VDC at 12 Amps. (probably why no vendor makes one)

And not safe unless isolated from mains.

What is the load?