Both boards are looking great!
Tim, glad to hear your eye is OK. With a board that size, can the ground plane sink enough heat for the regulators?
Yes, the board looks excellent!
Will you be providing a quality .pdf before the GND pour for closer inspection?
Both boards are looking great!
Tim, glad to hear your eye is OK. With a board that size, can the ground plane sink enough heat for the regulators?
Yeah, it should be able to. The heatsinks I've chosen actually have solder pins, so heat will be transferred directly into the top and bottom copper pours, which should greatly increase their effectiveness. I've run some numbers and we should be good for a 15VAC to 18VAC input range with a constant 400mA output on both regulators.
Your original hand drawn schematics didn't specify film
Whoops.
Both boards are looking great!
Tim, glad to hear your eye is OK. With a board that size, can the ground plane sink enough heat for the regulators?
Yeah, it should be able to. The heatsinks I've chosen actually have solder pins, so heat will be transferred directly into the top and bottom copper pours, which should greatly increase their effectiveness. I've run some numbers and we should be good for a 15VAC to 18VAC input range with a constant 400mA output on both regulators.
Great. I was curious because of Mike's comment regarding putting this into a low-profile enclosure. I'm not sure if he envisioned going lower than the heatsinks in the 3D drawing, but plenty of dissipation is good.
Could have just as well made them 0.1ohm resistors, so placing a volt meter on them will allow current measurements.
Originally I was going to use 0Ohm resistors, but ultimately a piece of wire is a lot less expensive, they have a very low voltage drop and allow a handy place to clip a probe as well!
You can still replace any of the wire jumpers with current shunt resistors if you want, as the footprints I've made will accept standard 1/4W resistors. (For footprints with 3.81mm or 5.08mm pad spacing the resistors could be placed in the vertical orientation, for 7.68mm and larger footprints the resistors could be placed in the normal horizontal orientation).
Originally I was going to use 0Ohm resistors, but ultimately a piece of wire is a lot less expensive, they have a very low voltage drop and allow a handy place to clip a probe as well!
You can still replace any of the wire jumpers with current shunt resistors if you want, as the footprints I've made will accept standard 1/4W resistors. (For footprints with 3.81mm or 5.08mm pad spacing the resistors could be placed in the vertical orientation, for 7.68mm and larger footprints the resistors could be placed in the normal horizontal orientation).
Is it possible to make them all the same footprint, say the standard horizontally mounted 1/4W resistor footprint?
Is it possible to make them all the same footprint, say the standard horizontally mounted 1/4W resistor footprint?
Is it possible to make them all the same footprint, say the standard horizontally mounted 1/4W resistor footprint?
Just to clarify what I meant by being able to use a normal resistor in place of the wire jumpers:
As you can see pad spacing is the same, so using resistors won't be an issue.
Keep in mind that 0Ohm resistors aren't actually zero ohm. Carbon ones can be close to 1Ohm in some cases! Metal film ones can be 250mOhm or more.
Keep in mind that 0Ohm resistors aren't actually zero ohm. Carbon ones can be close to 1Ohm in some cases! Metal film ones can be 250mOhm or more.
Keep in mind that 0Ohm resistors aren't actually zero ohm. Carbon ones can be close to 1Ohm in some cases! Metal film ones can be 250mOhm or more.
A quick look on Digikey for 1/4W zero ohm resistors gives 11 results, some carbon film, some metal foil. All have resistance of 20 milliohms or less.
Keep in mind that 0Ohm resistors aren't actually zero ohm. Carbon ones can be close to 1Ohm in some cases! Metal film ones can be 250mOhm or more.
A quick look on Digikey for 1/4W zero ohm resistors gives 11 results, some carbon film, some metal foil. All have resistance of 20 milliohms or less.
I said some.
It generally happens with the cheap grab bags you get from eBay or Ali Express. In a lot of cases they simply remark the lowest normal value they produce (often 500mOhm or 1Ohm) as zero. Other times they're simply QC rejects that have a manufacturing flaw and are resold in these lots.
If you're purchasing direct from Digi-Key you should be alright.
Just wanted to let you guys know I'm back working on the board again. I ended up having some work come up at the beginning of last week and haven't had any free time the past week. Now that things have calmed down I can finish the board up.
Just wanted to let you guys know I'm back working on the board again. I ended up having some work come up at the beginning of last week and haven't had any free time the past week. Now that things have calmed down I can finish the board up.
Thanks for the update, Tim. I still get a chuckle from your pretentiously polysyllabic profile prose. An amusingly astute archetype of alliteration it is.