If the board can sustain the inrush current, superb! (I don't like double boards either) My thought was simplistic: Never underestimate Mark, so if bigger buggers can't be on the board, then they maybe aren't supposed to be onboard (by design)...
@RickRay "to boldly go where …"
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Assuming that there is space in chassis and sufficient clearance to avoid EM pickup by signal wires, then I would do two boards for my own design.
Divides load between two boards, thereby reducing any concerns with copper trace handling and current limits, adapting and placing oversized current limiters, and arguably makes dual mono PS construction and troubleshooting easier. But I will admit these are simply preferences snd not hard limits requiring use of two boards; plus there is extra cost if boards, parts , and the space need (as mentioned above). In 4U Deluxe chassis, this may preclude use of double boards.
Divides load between two boards, thereby reducing any concerns with copper trace handling and current limits, adapting and placing oversized current limiters, and arguably makes dual mono PS construction and troubleshooting easier. But I will admit these are simply preferences snd not hard limits requiring use of two boards; plus there is extra cost if boards, parts , and the space need (as mentioned above). In 4U Deluxe chassis, this may preclude use of double boards.
I am not sure why there is the concern about copper traces.
My impression is that this circuit reduces high inrush current. Increasing the size of the CL is surely just going to slow the rate at which it heats up, therefore maintaining more modest `charge up' currents for longer. Using a 2Sec time delay and a big CL should enable a higher value of charge to be put into the smoothing capacitors while maintaining realistic values for current.
I can appreciate there is some question of how one solders the welding rod legs to the board without lifting the tracks -so going for two in series may be more realistic from a practical standpoint.
Maybe I'm missing something here.
My impression is that this circuit reduces high inrush current. Increasing the size of the CL is surely just going to slow the rate at which it heats up, therefore maintaining more modest `charge up' currents for longer. Using a 2Sec time delay and a big CL should enable a higher value of charge to be put into the smoothing capacitors while maintaining realistic values for current.
I can appreciate there is some question of how one solders the welding rod legs to the board without lifting the tracks -so going for two in series may be more realistic from a practical standpoint.
Maybe I'm missing something here.
A simplified procedure to calculate an approximate value for the peak inrush current, could look like this:
Plug in the numbers for your design and voila! You get a conservative over-estimate of peak inrush current. In reality the current will be smaller because those other resistances in the mains circuit aren't zero.
The mains current obeys Ohm's Law, even at turn-on: current = voltage / resistance. Voltage in this case is Vmains (115VAC or 230VAC) and resistance is the total of all the series circuit elements.
Making the ultra conservative assumption that the transformer core is fully saturated at the instant of turn-on, its resistance is reduced to R_primary_copper. Then
Total Resistance Seen By Mains = MainsFuseR + (IEC RFI suppressor R) + (R of chassis wiring) + (Trafo_primary_copper_R) + (ICL_resistance_when_cold)
Now, making another conservative assumption, let's pretend that all terms in the above summation are ZERO microhms, except (ICL_resistance_when_cold). We pretend all other resistances are negligibly small compared to the ICL cold resistance.
Ohm's Law tells us: current = voltage / resistance and in this case: Inrush_current <= Vmains / (ICL_resistance_when_cold)
Plug in the numbers for your design and voila! You get a conservative over-estimate of peak inrush current. In reality the current will be smaller because those other resistances in the mains circuit aren't zero.
LOL. We might be on different pages! I do appreciate your help, though!
Here is what I see in pfarrell's cart from the first page of the thread:
https://www.mouser.com/ProductDetail/689-TP2104N3-G
You can still purchase this product for backorder.
On Order: 1,991
Here is what I see in pfarrell's cart from the first page of the thread:
https://www.mouser.com/ProductDetail/689-TP2104N3-G
Availability
Stock: 0
Notify me when product is in stock.You can still purchase this product for backorder.
On Order: 1,991
Expected 10-Jun-24
So sorry, I should have posted more specifics. Here is what I'm seeing.
Granted, I had to go to another provider to get the datasheet to download, but with a VERY brief scan... with my untrained eye... here is what I saw in the data sheet for "P003". Right side, comparing example a to example b.
https://ww1.microchip.com/downloads...de-Vertical-DMOS-FET-Data-Sheet-20005958A.pdf
Again... I am TOTALLY not the guy to try and choose substitute parts. If it were just for me... I'd take the risk. Advising others... I'm not there yet.
Granted, I had to go to another provider to get the datasheet to download, but with a VERY brief scan... with my untrained eye... here is what I saw in the data sheet for "P003". Right side, comparing example a to example b.
https://ww1.microchip.com/downloads...de-Vertical-DMOS-FET-Data-Sheet-20005958A.pdf
Again... I am TOTALLY not the guy to try and choose substitute parts. If it were just for me... I'd take the risk. Advising others... I'm not there yet.
The only difference is that the ones with P003 in the part number are shipped to you on a paper tape that can be wound onto a reel, with the ones without P003 are shipped to you as loose individual TO-92's in a plastic bag. For the circuits used in this PCB, either one will be perfect. Buy what's cheapest or buy what's most easily available or buy what you find sexy.
I can only imagine "custom color" versions in the future... blue transistors to match your blue-mask PC board... LOL
No worries, IAIMH. I actually went for the exact part outside of Mouser, but you and Mark did teach me that the other part would have been available. As always, the education (of me) was worth your combined efforts. Many thanks.
You took care to get the correct ICL (115V/230V) I hope? (When I used pfarrells BOM/mouser cart, I did not and had to invent a new project to have it embedded in the shopping cart)…
Also, Mark often recommended us to use octoparts.com to hunt down parts…
(And I once went with red resistors to match the red PCB, but couldn’t go much further because the other parts (trimpots, capacitors etc.) are what they are, anything but red, 😂)
Also, Mark often recommended us to use octoparts.com to hunt down parts…
(And I once went with red resistors to match the red PCB, but couldn’t go much further because the other parts (trimpots, capacitors etc.) are what they are, anything but red, 😂)