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Electronics => Projects, Designs, and Technical Stuff => Topic started by: Hextejas on December 05, 2018, 01:41:03 pm

Title: Where to put a power-on LED
Post by: Hextejas on December 05, 2018, 01:41:03 pm
In this schematic.
I want to have some indication that the beast is on.

Thanks
Title: Re: Where to put a power-on LED
Post by: hayatepilot on December 05, 2018, 03:10:28 pm
Will the two rails be connected in series to have a symmetric voltages for a power amplifier? i.e. V+, GND, V-?
Then I would put the LED across V+ and V- so each rail is equally loaded. And in this case you could also save one Bridge rectifier.

Otherwise just put it across one of the rails. Judging from the grunty components you will probably not notice the tiny additional load on one rail.

Greetings
Title: Re: Where to put a power-on LED
Post by: ArthurDent on December 05, 2018, 06:02:35 pm
Because you have two separate identical power supplies that can output several amps of current, I would put a resistor/LED across each output. Where the two outputs are separate you will need two indicators to show that each of the two supplies is working.
Title: Re: Where to put a power-on LED
Post by: t1d on December 06, 2018, 12:19:02 am
Quote from: ArthurDent on December 05, 2018, 06:02:35 pm
Because you have two separate identical power supplies that can output several amps of current, I would put a resistor/LED across each output. Where the two outputs are separate you will need two indicators to show that each of the two supplies is working.
If panel space is tight, maybe you could use a two-color LED? That would show 4 states...
- Off/Both Failed
- Only one color, one side operational
- Only the other color, the other side operational
- The two colors making an averaged color, both sides operational.
Title: Re: Where to put a power-on LED
Post by: ArthurDent on December 06, 2018, 04:45:37 am
The problem with using one LED for 4 states is it's easy to forget which color means what. LEDs are small and cheap, use 2.
Title: Re: Where to put a power-on LED
Post by: ahbushnell on December 07, 2018, 03:07:41 am
Quote from: ArthurDent on December 06, 2018, 04:45:37 am
The problem with using one LED for 4 states is it's easy to forget which color means what. LEDs are small and cheap, use 2.
Or use one if he just wants to know if it's plugged in. 
Title: Re: Where to put a power-on LED
Post by: cdev on December 07, 2018, 03:48:49 am
Make it bright and red. For two supplies use two switches and LEDs in two places and I would even draw some boxes or put a line across the thing dividing its panel and clustering each supply's controls so you can clearly see which switch and which LED refers to which supply and that one or both are on. Thats it. Everybody does that for a reason. Don't confuse people.

Quote from: Hextejas on December 05, 2018, 01:41:03 pm
In this schematic.
I want to have some indication that the beast is on.

Thanks

Beasts.
Title: Re: Where to put a power-on LED
Post by: james_s on December 07, 2018, 05:39:53 am
Put it on either output, if one is on the other will be on too.

Or my own preference, put a neon indicator lamp across the primary.
Title: Re: Where to put a power-on LED
Post by: Hextejas on December 07, 2018, 11:02:57 am
Quote from: james_s on December 07, 2018, 05:39:53 am
Put it on either output, if one is on the other will be on too.

Or my own preference, put a neon indicator lamp across the primary.
Thank you all for the excellent comments. I was not clear in what i wanted. I just wanted it to indicate that it was turned on.
Whereas I had not considered showing that either/both rails was working.