Can I get X7R for all ceramic capacitors? And should both my fuses(mains, transformer secondary) be slow blow?

I suggest standard fuses, neither slo-blo nor fast. There is nothing in this system, at least so far, that draws a high startup current for any longer length of time, and in addition there is nothing that is likely to produce a shorted circuit that will need instant protection of upstream items.

 

Generally, yes to X7R and standard is fine.

Are you going SMD or through-hole?

 

I suggest standard fuses, neither slo-blo nor fast. There is nothing in this system, at least so far, that draws a high startup current for any longer length of time, and in addition there is nothing that is likely to produce a shorted circuit that will need instant protection of upstream items.

Thanks. Wouldn't the ballasts draw high startup currents? It's not going to be on this board but I'm planning to add a fuse there as well.

Generally, yes to X7R and standard is fine.

Are you going SMD or through-hole?

Thanks! SMD

 

Thanks! SMD

Have you laid out a PCB before of any sort? I think not IIRC! That'll be a whole new war & peace sized thread!

 

Have you laid out a PCB before of any sort? I think not IIRC! That'll be a whole new war & peace sized thread!

I have once earlier. But it was around an year before. I have forgotten how I did it.
Ha ha. I hope it's going to be interesting and I will be learning a lot.

 

I have done some changes to the design. The lamps would be drawing only 1.92A(nominal current) totally. Would I still need a relay rated for 20A ? Would it not be better to downsize the relays? Also, can pilot duty loads be considered as a load that is similar to the electronic ballasts?

Thanks

 

how have you reduced it?

 

how have you reduced it?

I replaced the lamps with different ones. They still use a electronic ballast though. The datasheet of the lamp states nominal current draw as 0.4A(4 lamps) and 0.16A for another type(2 Lamps). So, 1.92A in total.

 

One of the benefits of electronic ballasts is indeed the reduction of the turn-on higher load. As long as you have five of them switching on through one set of contacts that is still almost ten amps steady state. For the longest contact life and the best reliability you still need a safety factor. So having at least 15 amp rated contacts make sense. Having an adequate safety factor is the cheapest way to improve reliability and assure a longer product life.

 

One of the benefits of electronic ballasts is indeed the reduction of the turn-on higher load. As long as you have five of them switching on through one set of contacts that is still almost ten amps steady state. For the longest contact life and the best reliability you still need a safety factor. So having at least 15 amp rated contacts make sense. Having an adequate safety factor is the cheapest way to improve reliability and assure a longer product life.

The 1.92 A is the total for consumption of all 6 lamps. They individually consume 0.4, 0.4, 0.4, 0.4, 0.16, 0.16 A.

 

The 1.92 A is the total for consumption of all 6 lamps. They individually consume 0.4, 0.4, 0.4, 0.4, 0.16, 0.16 A.

OK, then I misread the current as per each. Then ten amp contacts will provide a good safety margin.

 

OK, then I misread the current as per each. Then ten amp contacts will provide a good safety margin.

Great. I would downsize to 10A then. Right now, its 20A.

 

I have a 10A fuse on the mains, now that the current consumption has come down would a 5A standard fuse be better choice? I have also got a 2A standard fuse on individual lamps, planning to reduce it to 1.5A. I thought of removing it but they are not expensive and helps run rest of the lamps when only one fails.

Thanks.

 

I have a 10A fuse on the mains, now that the current consumption has come down would a 5A standard fuse be better choice? I have also got a 2A standard fuse on individual lamps, planning to reduce it to 1.5A. I thought of removing it but they are not expensive and helps run rest of the lamps when only one fails.

Thanks.

Those values that you have now are reasonable, so no need to change them. Kep in mind that a fuse is intended to stop the spread of damage in the event of a short-circuit failure.

 

Great. I would downsize to 10A then. Right now, its 20A.

be careful when you downsize. Some of the 10A relays were particularly poorly rated for use with the ballast.

 

Those values that you have now are reasonable, so no need to change them. Kep in mind that a fuse is intended to stop the spread of damage in the event of a short-circuit failure.

Thanks.

be careful when you downsize. Some of the 10A relays were particularly poorly rated for use with the ballast.

Thanks. I checked the datasheet and its rated 10A for a load with 0.4 powerfactor for 25000 cycles.

If I plan to use a reflow oven, do I need to be careful while selecting components? Can all components be soldered with a reflow oven?

 

If I plan to use a reflow oven, do I need to be careful while selecting components? Can all comp

Most SMD parts will go through a reflow oven though it's advisable to check the profile on anything exotic to make sure it's compatible with the general stuff. I did have some connectors once that melted though their profile said they shouldn't have, I think they might have been fake.

 

Most SMD parts will go through a reflow oven though it's advisable to check the profile on anything exotic to make sure it's compatible with the general stuff. I did have some connectors once that melted though their profile said they shouldn't have, I think they might have been fake.

ok, Thanks

 

I was going to add that through-hole parts are add after reflow as many of those can't go through the oven. Which is why you also need a hot-air rework station, or a micro-soldering iron, for changes and repairs later. A good microscope is useful too if your eyesight is like mine!

 

My experience with surface mount devices is that the solder past application and part placement effort, are far more work than building a circuit board with through-hole components. If it will be an automated production process that would be different, but it seems like the TS is only planning on producing a few of these systems.
If the assembly will be manual then it is far easier to get a good production yield with the through hole parts, since the spacing is a bit greater.