| Electronics > Beginners |
| Looking for 30V 5A schematic |
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| not1xor1:
--- Quote from: b_force on October 06, 2017, 08:15:32 pm ---This is an interesting transformer to use. Price is decent https://www.digikey.nl/product-detail/en/triad-magnetics/F-360U/F-360U-ND/7318113 Other idea is just simply buy a (second hand) Chinese PSU and use your own (better) schematic. I have seen some for around 50 bucks, just a transformer and a case would be more expensive. edit: I mean, something like this. 43 bucks for 5A. https://www.amazon.com/ZTDM-QW-MS305D-Stabilizer-Precision-Adjustable/dp/B06VXGLFWK/ --- End quote --- be careful those cheap PSUs are not linear PSUs if you check one of the pictures you can see, through the ventilation slots, that the case is almost empty no 50/60 Hz multi tapped transformer, no large heatsink I think linear PSUs are more expensive nowadays even second hand ones you can grab on ebay, at least here in Europe, cost more than 50-60 euros (including shipping expenses) |
| Kleinstein:
One can still get linear and SMPS based cheap lab supplies. The higher power ones (e.g. > 200 W) are usually switched mode. With the linear type the small ones (like 50 W) are still cheap, by the higher power one get more expensive. One can usually tell from the weight if it is a linear or SMPS type. It also gives a clue on the size of the transformer and might be a warning if a unit is rather low weight for the claimed power, it might use excessive load to the transformer (and often other part too). However toroid shaped transformers are actually lower weight - so you can't buy by the kg only. |
| b_force:
--- Quote from: not1xor1 on October 08, 2017, 08:13:41 am --- --- Quote from: b_force on October 06, 2017, 08:15:32 pm ---This is an interesting transformer to use. Price is decent https://www.digikey.nl/product-detail/en/triad-magnetics/F-360U/F-360U-ND/7318113 Other idea is just simply buy a (second hand) Chinese PSU and use your own (better) schematic. I have seen some for around 50 bucks, just a transformer and a case would be more expensive. edit: I mean, something like this. 43 bucks for 5A. https://www.amazon.com/ZTDM-QW-MS305D-Stabilizer-Precision-Adjustable/dp/B06VXGLFWK/ --- End quote --- be careful those cheap PSUs are not linear PSUs if you check one of the pictures you can see, through the ventilation slots, that the case is almost empty no 50/60 Hz multi tapped transformer, no large heatsink I think linear PSUs are more expensive nowadays even second hand ones you can grab on ebay, at least here in Europe, cost more than 50-60 euros (including shipping expenses) --- End quote --- I actually thought that most linear PSUs were the cheap ones, lol my bad. I have seen linear PSUs for cheap as well, somewhere |
| Kleinstein:
There are cheap small linear power supplies, like 0-18 V and 2 A. I found one in Germany for just under 30 EUR. However they get more expensive when they get larger. So the 30 V 3 A Version is more like $100 in a linear version. SMPS based versions can be cheaper in this power range. So the cheap one in the 100-200 W range are usually SMPS based ones. It is usually easy to tell by the weight. A pure switched mode regulator will give quite some output ripple and the speed of the regulation and thus transient response is limited. Filtering the Ripple will slow down the transient response - so there are limits one how much can be done. To reduce these two principle weak points, there are also supplies with a SMPS regulator followed by a linear stage. This way ripple can be low, regulation fast (least least most of the time, if the step is not to large up in power) without a massive heat sink and noisy fan. However these supplies are usually not the very cheap ones. |
| b_force:
It would be interesting to find out if you can make these switching PSUs like a tracking psu. Than it's just simply adding a decent good performing regulator to suppress the ripple and noise and you're done. |
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