I'm going to be building "The Wire" and I'm trying to come up with a way to integrate an LED. I'm going to use this ±15V power supply that I don't think comes with an LED.
PS-12 Bipolar Low-Voltage PS
So I'm thinking that the LED would have to fall somewhere between this supply and the amp. How would I wire it in? To make my calculation for my LED resistor I'm assuming my source voltage would be the +15V from the supply. The LED I want to use has a forward voltage of 2V and a forward current of 10mA, so I'd need a 1.5k ohm 1/2W resistor to do the trick. Are my assumptions correct?
Also, I want to try and put this in the smallest case possible. Would this work for my power connector?
6160.0012 Schurter Power Entry Modules
I'd like to avoid using the standard IEC socket, but if this socket doesn't work then what part is the smallest and works best?
TIA,
Mullet
PS-12 Bipolar Low-Voltage PS
So I'm thinking that the LED would have to fall somewhere between this supply and the amp. How would I wire it in? To make my calculation for my LED resistor I'm assuming my source voltage would be the +15V from the supply. The LED I want to use has a forward voltage of 2V and a forward current of 10mA, so I'd need a 1.5k ohm 1/2W resistor to do the trick. Are my assumptions correct?
Also, I want to try and put this in the smallest case possible. Would this work for my power connector?
6160.0012 Schurter Power Entry Modules
I'd like to avoid using the standard IEC socket, but if this socket doesn't work then what part is the smallest and works best?
TIA,
Mullet
That power connector will not work. It is a 2-pin connector, and you need a 3-pin connector (+15/Gnd/-15).
A mini-DIN may be your best bet for a small power connector that's readily available and reasonably priced.
I would connect the LED across +15 and -15. That would be with a 2800-ohm (1%) or 2700-ohm (5%) resistor. 1/2W power rating.
A mini-DIN may be your best bet for a small power connector that's readily available and reasonably priced.
I would connect the LED across +15 and -15. That would be with a 2800-ohm (1%) or 2700-ohm (5%) resistor. 1/2W power rating.
I think with reference to the larger "IEC socket" the OP wants to use the connector for line power which then goes to a small power transformer to power the regulator board. I certainly would argue against using the standard IEC power input connector for anything but line voltage power input.
Is this thing going in a metal chassis? A metal chassis is good for audio shielding, but as I recall, any metal box that has 120VAC or 240VAC coming into it has to have the chassis tied to the ground of the power cable as a safety measure, so that an internal fault doesn't put line voltage on the chassis where someone could touch it.
Mull3t, maybe you could clear up what exactly is going in the case. This power supply board certainly, but also the power transformer that feeds it? "The Wire" also? What material will the case be made of?
Is this thing going in a metal chassis? A metal chassis is good for audio shielding, but as I recall, any metal box that has 120VAC or 240VAC coming into it has to have the chassis tied to the ground of the power cable as a safety measure, so that an internal fault doesn't put line voltage on the chassis where someone could touch it.
Mull3t, maybe you could clear up what exactly is going in the case. This power supply board certainly, but also the power transformer that feeds it? "The Wire" also? What material will the case be made of?
Ok, so it looks like the best option is an IEC socket. Something like this...
161-R30148-E Kobiconn Power Entry Modules
The mini-DIN looks interesting but would require more jiggering to get it to work. Where as with the IEC socket all I'd need is a power cable. Is there a better option as far as IEC C-14 sockets go?
As far as the LED goes... I'm still confused on wiring. My weird logic says you'd need two wires coming out of +15V and two coming out of -15V. One set goes to the LED and the other goes to the amp board. The resistor is on the +15V wire.
Thanks,
Mullet
161-R30148-E Kobiconn Power Entry Modules
The mini-DIN looks interesting but would require more jiggering to get it to work. Where as with the IEC socket all I'd need is a power cable. Is there a better option as far as IEC C-14 sockets go?
As far as the LED goes... I'm still confused on wiring. My weird logic says you'd need two wires coming out of +15V and two coming out of -15V. One set goes to the LED and the other goes to the amp board. The resistor is on the +15V wire.
Thanks,
Mullet
Here's a clarification of what is going on with this amp.
"The Wire" starts out with a 15-0-15 transformer that goes into a bipolar ±15V supply that goes into the amplifier board.
I would think that line voltage is going into the transformer so then the IEC socket is probably needed. I have to have the ground pin tied to the case, right? I plan on using the smallest case possible. I haven't figured out what yet and figured I'd do that once the amp is built and working then I could figure out my casing. I know it will be metal at least. Maybe something from Hammond or Box Enclosures.
"The Wire" starts out with a 15-0-15 transformer that goes into a bipolar ±15V supply that goes into the amplifier board.
I would think that line voltage is going into the transformer so then the IEC socket is probably needed. I have to have the ground pin tied to the case, right? I plan on using the smallest case possible. I haven't figured out what yet and figured I'd do that once the amp is built and working then I could figure out my casing. I know it will be metal at least. Maybe something from Hammond or Box Enclosures.
I misunderstood. You're looking for an AC input connector. The power entry module in post #1 will work, then. It is a good safety measure to connect the metal case to protective earth, but it's not absolutely necessary unless you plan to ship your Wire off for UL approval. Some here may jump up and down over that statement, but that's the truth of the matter. Just be sure an internal fault doesn't put line voltage on the case (which isn't terribly difficult). If you doubt your abilities in the slightest, by all means use a grounded 3-wire cord.
You need 3 wires from the bipolar supply to the amp. I explained the LED hookup.
You need 3 wires from the bipolar supply to the amp. I explained the LED hookup.
If it were me I'd use a 3 conductor grounded cord and a std IEC power entry. The "shaver" type power entry module shown in post #1 is for products that are double insulated, which your home brew stuff will not be. If you are trying to save space skip the power entry module and use a strain relief to connect the power cord to your chassis.
This is where I'm going to show my newbishness. Can you further elaborate on connecting the LED "across" +15 and -15. My guess is that I could connect my + wire and - wire from my power supply and connect that to the ampflier board. Then on the underside of the power supply board where my + point is and - point is wire in my LED there.
Three wires will go to your amp board... +15V and 0V and -15V.
If you understand that part of the hookup, mentally set it aside for the rest of this post.
If you don't understand it (or if I don't), state so in a reply.
The resistor and LED will connect across +15V and -15V like this: +15 ---/\/\/\--->|--- -15
Your "guess" sounds fine, and is probably how I would do it. When you've inserted the amplifier power wires into the supply board, the wire ends on the bottom side will create small posts that you can connect the LED wiring to.
No, they're pretty standard.
Use a fuse!
Ben, you have a good point.
sofaspud, this is exactly how I will do it then. I've also gotten a tip from a fellow diyaudio forum member to use two resistors, one on each side of the LED in order to take the load off one side of the LED. Wouldn't a zener diode or two help here too? I'm assuming that might be another way to skin a cat.
sofaspud, this is exactly how I will do it then. I've also gotten a tip from a fellow diyaudio forum member to use two resistors, one on each side of the LED in order to take the load off one side of the LED. Wouldn't a zener diode or two help here too? I'm assuming that might be another way to skin a cat.
"...Take the load off one side of the LED"? I haven't the slightest idea what that is supposed to mean. The fact that it wasn't posted here in the light should tell you something. There is no load on "one side of the LED," except the resistor i showed you in a previous post. And it's the only resistor you need. Other resistors and diodes in series would work to drop some voltage, but you definitely don't need them.
Hmm, there's this thing call Kirchoff's Current Law, that suggests to me it doesn't matter how many resistors are in a series circuit, nor what each value is as long as their resistance totals the same, the current through the circuit will be the same. Yes, you could use a zener diode to drop some voltage, but I don't see any advantage to that.
You can run the LED on a single regulator output, putting an extra 10mA load on it, or across the +15 and -15 regulated outputs putting 10mA on BOTH outputs (which appeals to the philosophical idea of symmetrical loading), or you could connect it to the INPUTS of the regulators, or even across the AC secondary (with a revesed diode across the LED to prevent too-high reverse voltage), which would make the LED flash at 50/60Hz.
Any of these will work, with an appropriately sized (resistance and power rating) series resistor. As "you can call me Bobby" says in his song while imitating some other pop-culture character, you doesn't have to call me Johnston.
You can run the LED on a single regulator output, putting an extra 10mA load on it, or across the +15 and -15 regulated outputs putting 10mA on BOTH outputs (which appeals to the philosophical idea of symmetrical loading), or you could connect it to the INPUTS of the regulators, or even across the AC secondary (with a revesed diode across the LED to prevent too-high reverse voltage), which would make the LED flash at 50/60Hz.
Any of these will work, with an appropriately sized (resistance and power rating) series resistor. As "you can call me Bobby" says in his song while imitating some other pop-culture character, you doesn't have to call me Johnston.
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