I'm guessing that the use of square vias versus circular vias is a following a convention for indicating positive and negative... I just have no idea what the convention _is_. Given that this will be assembled by amateur builders, you have a little board real estate between the silk screening of 5VDC and 12VDC - suggest you add silk screening to indicate that [] is + and O is - (or vice versa...). That way, there's no ambiguity.
Thank you, that's an excellent point. I definitely plan to have detailed construction documentation, but more clarity is always better than less, especially when it comes to wiring up power.
The order of the LEDs certainly be changed. That was the easiest routing at the time but it probably does make more sense to have them be in the same order.
Regarding adding 9 V, I don't have any plans to have 9V modules to my list of boards, but it could be added to a second, larger power distribution board option, if the need was really there.
As far as the number of power pins goes, I'm basing this on what I estimate will be used by each module in the radio designs that I have planned. Most modules will only use 12 VDC, which is why they are the most prominent. Again, this is a preliminary design and things can be modified if it turns out that it's not adequate. I am considering adding a second, parallel power header on each module so that power between modules could be shared that way, instead of having all of the power fan out from the power distribution board.
The 2A power supply is a minimum, so if you can provide a more capable 12 VDC input, it can definitely be used.
What are you using for your reference signal generator? I've been looking around for amaster TCXO for an SDR project, but haven't found anything that really stands out.
2 x RFZero and N6GN-reference board in combination with a not new OCXO from a 'Chinese friend', but also the 1 pps signal from cheap gps boards with ublox chips and GPS-boards from QRP-labs (Hans Summers).
I don't have a standalone ref osc of my own design in the works for this project. I personally have a Thunderbolt GPSDO that I use in the shack, but I expect a good alternative for those who don't have one is something like the Leo Bodnar GPSDO.
This would probably be better than the three 3A DC-DC LM2596 Buck converters (for 12v, 5v, and 3.3v) I'm using for one of my Digital radio/sdr go box projects. Too much clutter at the moment. Would the components be able to handle 5A max across all rails?
Hi Jason, I'm not sure you are going to do 3V3 @ 500mA. With 12V in and 3V3 out that's 8.7V dropped across the regulator. The power in the reg will be 8.7V x 0.5A = 4.35W. The datasheet for the AP2213 talks about ThetaJC being 45 degC/W so we are talking close to 200degC. Alan ZL3UYJ
Thank you for the sanity check, I think I was getting a bit crazy with that spec and forgot that I won't really need that much current. Now that things are coming a bit more into focus, I think I only need more current capacity on the 5V rail, not the 3.3V rail. I think it's going to be more like 100 mA, which should be more than enough for the potential 3.3V devices connected.
I'm guessing that the use of square vias versus circular vias is a following a convention for indicating positive and negative... I just have no idea what the convention _is_. Given that this will be assembled by amateur builders, you have a little board real estate between the silk screening of 5VDC and 12VDC - suggest you add silk screening to indicate that [] is + and O is - (or vice versa...). That way, there's no ambiguity.
Thank you, that's an excellent point. I definitely plan to have detailed construction documentation, but more clarity is always better than less, especially when it comes to wiring up power.
Posted an updated rendering in chat.
1. Why is the order of the leds different from the order of the power rails ? That is confusing.
2. I have much SDR equipment and GPS and 10 MHz references needing 9V. Could that be something to add.
I also have a lot of 5 V like Raspberry Pi, Red Pitaya, GPS modules.
The 5V + 9V pieces are a lot more in need than 12V at my shack desk. So I would prefer (oh dear) less 12V pins and more 5 and 9V pins.
But I also realize these might together need more than the 2A your interesting design is going to provide.
Thanks for the comments!
The order of the LEDs certainly be changed. That was the easiest routing at the time but it probably does make more sense to have them be in the same order.
Regarding adding 9 V, I don't have any plans to have 9V modules to my list of boards, but it could be added to a second, larger power distribution board option, if the need was really there.
As far as the number of power pins goes, I'm basing this on what I estimate will be used by each module in the radio designs that I have planned. Most modules will only use 12 VDC, which is why they are the most prominent. Again, this is a preliminary design and things can be modified if it turns out that it's not adequate. I am considering adding a second, parallel power header on each module so that power between modules could be shared that way, instead of having all of the power fan out from the power distribution board.
The 2A power supply is a minimum, so if you can provide a more capable 12 VDC input, it can definitely be used.
73,
Jason NT7S
What are you using for your reference signal generator? I've been looking around for amaster TCXO for an SDR project, but haven't found anything that really stands out.
2 x RFZero and N6GN-reference board in combination with a not new OCXO from a 'Chinese friend', but also the 1 pps signal from cheap gps boards with ublox chips and GPS-boards from QRP-labs (Hans Summers).
I don't have a standalone ref osc of my own design in the works for this project. I personally have a Thunderbolt GPSDO that I use in the shack, but I expect a good alternative for those who don't have one is something like the Leo Bodnar GPSDO.
This would probably be better than the three 3A DC-DC LM2596 Buck converters (for 12v, 5v, and 3.3v) I'm using for one of my Digital radio/sdr go box projects. Too much clutter at the moment. Would the components be able to handle 5A max across all rails?
Hi Jason, I'm not sure you are going to do 3V3 @ 500mA. With 12V in and 3V3 out that's 8.7V dropped across the regulator. The power in the reg will be 8.7V x 0.5A = 4.35W. The datasheet for the AP2213 talks about ThetaJC being 45 degC/W so we are talking close to 200degC. Alan ZL3UYJ
Thank you for the sanity check, I think I was getting a bit crazy with that spec and forgot that I won't really need that much current. Now that things are coming a bit more into focus, I think I only need more current capacity on the 5V rail, not the 3.3V rail. I think it's going to be more like 100 mA, which should be more than enough for the potential 3.3V devices connected.