| Electronics > Beginners |
| Generating 3 voltage rails, will this work ? |
| << < (4/5) > >> |
| BravoV:
--- Quote from: bd139 on July 02, 2018, 08:15:58 am ---Ideal world: Meanwell RT-65C + pi network LC filters on the +15V, -15V outputs. --- End quote --- Agree, its just I already have the suitable (ideal) transformer collecting dust, and a really-really damn cheap NOS Vicor isolated DC to DC converter. |
| bd139:
Yeah that was a bargain :) |
| David Hess:
--- Quote from: BravoV on July 02, 2018, 08:04:48 am --- --- Quote from: David Hess on July 01, 2018, 04:38:02 pm ---I would start with an LCR decoupling network at the input to the switching voltage regulator to isolated it from the inputs to the linear regulators. --- End quote --- Something like this ? Added L4 ? --- End quote --- Exactly. --- Quote ---You mentioned LCR .. where the R part should be placed ? --- End quote --- The resistor goes across the inductor to limit Q and prevent noise peaking. The value can be selected based on the self resonate frequency since above this point, the inductor looks capacitive anyway. Or just assume that you will never get more than 20 or 30 dB of attenuation and treat it as an RC filter with the inductor shorting out the resistance at low frequencies to prevent excessive voltage drop. --- Quote ---Also L6 to reduce the output switching noise. --- End quote --- There is nothing wrong with that. |
| OuchItReallyHz:
--- Quote from: Ian.M on June 30, 2018, 07:58:52 am ---Unless you've got a 15-0-15V >60VA transformer + the 30 to 48V in, 5A@5V out DC-DC converter hanging about essentially free, it probably doesn't make much sense to do it that way. If the transformer is run too close to its rating, the 7815 and 7915 regulators will be prone to dropout at the ripple troughs if the 5V rail is heavily loaded, so I suspect a 50VA transformer would be marginal. The easy low cost option would be a 19V small laptop PSU, 7815 for a clean +15V rail, buck converter for the +5V rail and inverting switching regulator to get a -18V feed to a 7915 for a clean -15V rail. --- End quote --- What inverting switching regulator would be a good option? I'm looking for something like this as well, +/- 15V, but haven't come up with anything simple save for a AC transformer, but as a relative noob, I'd rather not deal with the weight and issues of a transformer. |
| bd139:
TI do a range of SMPS parts that just work http://www.ti.com/ww/en/simple_switcher/index.html?HQS=sva-bmp-sspl-simpleswitcher-vanity-lp-null-wwe# |
| Navigation |
| Message Index |
| Next page |
| Previous page |