How do I make an Equipment ground

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
I am building the Elenco AM/FM radio kit. And for a static power test it is telling me to connect my equipment ground to circuit ground test point 15 while the circuit is being powered by a 9volt battery. . I’m just pretty confused on what it means by “equipment ground” and what I can do to satisfy this. I have a DC power supply unit that has a ground terminal can I use that? I am a beginner and have very little knowledge so explain it like you’re explaining it to a five-year-old please. Thank you for your time and help!image.jpgimage.jpgimage.jpg
 

ericgibbs

Joined Jan 29, 2010
16,002
hi bb,
Welcome to AAC
what it means by “equipment ground”

Any external equipment you are using to test the unit, eg: sine wave generator. Meter, Scope etc,,
E

Update:
This may help explain.

EG57_ 16.pngEG57_ 17.png
 
Last edited:

SamR

Joined Mar 19, 2019
4,336
PSU's usually have 3 output terminals. The + & - are relative. The GND is tied to the 3rd pin of the wall plug (US) which is tied to earth ground at the distribution panel.

And Welcome to AAC!
 

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
hi bb,
Welcome to AAC
what it means by “equipment ground”

Any external equipment you are using to test the unit, eg: sine wave generator. Meter, Scope etc,,
E

Update:
This may help explain.

View attachment 273826View attachment 273827
Thank you for the reply and the welcome! The image in figure 6 shows me using both my meter test leads onto the circuit so how would I also have a test lead going to TP15? I feel like I’m really overthinking this and it’s driving me crazy
 

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
PSU's usually have 3 output terminals. The + & - are relative. The GND is tied to the 3rd pin of the wall plug (US) which is tied to earth ground at the distribution panel.

And Welcome to AAC!
Thank you for the welcome! Does that mean the PSU GND terminal can be used as a earth ground point?
 

MisterBill2

Joined Jan 23, 2018
12,697
Really, "ground" is an incorrect term. What was meant was the power source common, which in this case is the battery negative side, and in the picture that part of the circuit connected to TP15 is hidden beneath a finger. The correct term for this circuit is "supply negative, which can also be called "common"
 

SamR

Joined Mar 19, 2019
4,336
Does that mean the PSU GND terminal can be used as a earth ground point?
Yes. As Bill pointed out, GND is relative. For +Voltage circuits (which is what you have) the -Terminal is usually the relative ground for the circuit. The circuit itself is "floating" and NOT grounded to earth. Which is normal for any battery powered circuit. You don't want to be hammering a ground rod in the ground every time you turn a portable battery powered device on outside or even inside the home.

When you use the + & - terminals of the PSU you can generate positive or negative voltage depending on how the PSU is connected to the circuit. But it is NOT connected to earth ground unless you use the GND terminal of the PSU.
 

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
Really, "ground" is an incorrect term. What was meant was the power source common, which in this case is the battery negative side, and in the picture that part of the circuit connected to TP15 is hidden beneath a finger. The correct term for this circuit is "supply negative, which can also be called "common"
Sorry about the finger was trying to indicate the TP15. image.jpgimage.jpg
 

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
Yes. As Bill pointed out, GND is relative. For +Voltage circuits (which is what you have) the -Terminal is usually the relative ground for the circuit. The circuit itself is "floating" and NOT grounded to earth. Which is normal for any battery powered circuit. You don't want to be hammering a ground rod in the ground every time you turn a portable battery powered device on outside or even inside the home.

When you use the + & - terminals of the PSU you can generate positive or negative voltage depending on how the PSU is connected to the circuit. But it is NOT connected to earth ground unless you use the GND terminal of the PSU.
If I wanted an earth ground for a different +volt circuit later on I would use the +terminal and the GND terminal on my PSU, and leave out the -terminal?
 

ericgibbs

Joined Jan 29, 2010
16,002
hi bb,
Just follow the Build Instructions and use TP15 as a Ground reference point for all your equipment measurements.

E

Update:

Don't confuse Earth and Ground designators, they are very different meanings
Ground usually refers to a Common point of reference.




EG57_ 19.png
 

MrChips

Joined Oct 2, 2009
26,790
The word “ground” is used for different purposes in different circumstances. This can lead to confusion.

  1. electrical connection to earth potential
  2. a reference point for all voltage measurements, signal common
  3. return path to a power supply

Your bench power supply may have a ground connection. This is not necessarily the same as power ground or signal common.

Show us a photo or link to your power supply.
 

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
The word “ground” is used for different purposes in different circumstances. This can lead to confusion.

  1. electrical connection to earth potential
  2. a reference point for all voltage measurements, signal common
  3. return path to a power supply

Your bench power supply may have a ground connection. This is not necessarily the same as power ground or signal common.

Show us a photo or link to your power supply.
https://www.amazon.com/Interface-Ad...cphy=9011827&hvtargid=pla-1455170653142&psc=1
 

Ya’akov

Joined Jan 27, 2019
6,266
Welcome to AAC.

That Elenco kit is great. We used that as a final project for second year EE students. They had to build it, then explain the circuit by answering questions about what various components did in their context.

It's also really cool that they label the stages at the top and bottom so you can understand the functions of the sub-circuits.

If you spend time actually learning about the circuits, you will get a lot out of it. It's very well done and by the time you go from antenna to audio amplifier for both AM and FM you will have a solid background in basic electronics and how radios operate. After you build the kit, you still have that to do!
 

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
Welcome to AAC.

That Elenco kit is great. We used that as a final project for second year EE students. They had to build it, then explain the circuit by answering questions about what various components did in their context.

It's also really cool that they label the stages at the top and bottom so you can understand the functions of the sub-circuits.

If you spend time actually learning about the circuits, you will get a lot out of it. It's very well done and by the time you go from antenna to audio amplifier for both AM and FM you will have a solid background in basic electronics and how radios operate. After you build the kit, you still have that to do!
I agree, I literally had no idea how any of this worked before I started these little kits and I’ve definitely learned a lot since then. Photo is of the first kit I made, pretty fun! I’ve only been in this community for a couple hours now but you guys are all pretty awesome and helpful!
 

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MrChips

Joined Oct 2, 2009
26,790
Bench power supplies are usually designed as “floating” power supplies.
It is important that you understand what this means and it’s consequences.

Before we begin the discussion, let us confirm that the PSU is floating.
Disconnect the PSU from your AC wall socket.
With a DMM set to measure low resistance or continuity, confirm that the ground plug on the power cord shows 0 or close to 0 ohms between it and the ground banana post on the front panel.

Set the DMM to read 100VDC or about that range.
Plug in the PSU to AC power and set the voltage and current output to midrange. Confirm that the output voltage is correct by measuring the voltage out between the + and - posts.

Next, measure the voltage between + and GND.
Then measure the voltage between - and GND.
In both cases the voltage reading should be close to zero volts.
This concludes the tests and confirms that the PSU is ”floating”.

Now on with the discussion.
A typical battery such as a 9V battery is a floating power source.
There is no reference to earth potential.

Your radio kit while powered with a 9V battery is a floating circuit.
Your radio kit powered by a floating PSU is a floating circuit.
You can turn a floating power supply or 9V battery into a positive supply referenced to earth potential. To do this, connect a jumper wire between the - post or terminal to earth ground. It is common practice to do this permanently on the PSU by leaving a permanent strap between - and GND on the PSU. Just be aware that you have done this. In future there may be a situation when you may want to remove the strap.

(I am on the road and I am typing on a tablet hence this limits how much I can type and edit.)
 

Thread Starter

binksterbinks

Joined Aug 14, 2022
16
Bench power supplies are usually designed as “floating” power supplies.
It is important that you understand what this means and it’s consequences.

Before we begin the discussion, let us confirm that the PSU is floating.
Disconnect the PSU from your AC wall socket.
With a DMM set to measure low resistance or continuity, confirm that the ground plug on the power cord shows 0 or close to 0 ohms between it and the ground banana post on the front panel.

Set the DMM to read 100VDC or about that range.
Plug in the PSU to AC power and set the voltage and current output to midrange. Confirm that the output voltage is correct by measuring the voltage out between the + and - posts.

Next, measure the voltage between + and GND.
Then measure the voltage between - and GND.
In both cases the voltage reading should be close to zero volts.
This concludes the tests and confirms that the PSU is ”floating”.

Now on with the discussion.
A typical battery such as a 9V battery is a floating power source.
There is no reference to earth potential.

Your radio kit while powered with a 9V battery is a floating circuit.
Your radio kit powered by a floating PSU is a floating circuit.
You can turn a floating power supply or 9V battery into a positive supply referenced to earth potential. To do this, connect a jumper wire between the - post or terminal to earth ground. It is common practice to do this permanently on the PSU by leaving a permanent strap between - and GND on the PSU. Just be aware that you have done this. In future there may be a situation when you may want to remove the strap.

(I am on the road and I am typing on a tablet hence this limits how much I can type and edit.)
Thank you for the reply. While doing the first test you suggested (test ground port and ground on plug) the numbers go from 0.6 all way up to 250.0 I can’t get it to settle on a value. image.jpgimage.jpgimage.jpgimage.jpg
 
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