connecting dc supplies in parallel for more current
 

Im still trying to come up with a high current DC supply for my mobile HF rig.
I have 4 - transformers that are all the same part number, there output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like it would
work ok, Im not sure about paralleling DC supplies ?

You can probably make it work with matched parts, but you will need
somevery good heatsinking and a crowbar circuit in case one of your pass
regulators shorts out.

You should really look at using an ASTRON SS30 or SS30M (M has volt and
amp meters). One was for sale on one of the swap boards recently. I have
two and they deliver the current without any strain or heat. As far as
RFI noise, they are also very quiet. ARRL did a write up a couple years
back on various switchers and this one was the quietest. 25 amps
continuous, 30 amps intermittent. I run mine to 20 amps all the time and
the fan switches on for a short time, no sweat.

clc wrote:

Im still trying to come up with a high current DC supply for my mobile HF rig.
I have 4 - transformers that are all the same part number, there output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like it would
work ok, Im not sure about paralleling DC supplies ?




--
Joe Leikhim K4SAT


"Jazz is not dead. It just smells funny." -F.Z.

You can probably make it work with matched parts, but you will need
somevery good heatsinking and a crowbar circuit in case one of your pass
regulators shorts out.

You should really look at using an ASTRON SS30 or SS30M (M has volt and
amp meters). One was for sale on one of the swap boards recently. I have
two and they deliver the current without any strain or heat. As far as
RFI noise, they are also very quiet. ARRL did a write up a couple years
back on various switchers and this one was the quietest. 25 amps
continuous, 30 amps intermittent. I run mine to 20 amps all the time and
the fan switches on for a short time, no sweat.

clc wrote:

Im still trying to come up with a high current DC supply for my mobile HF rig.
I have 4 - transformers that are all the same part number, there output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like it would
work ok, Im not sure about paralleling DC supplies ?




--
Joe Leikhim K4SAT


"Jazz is not dead. It just smells funny." -F.Z.

clc wrote:

Im still trying to come up with a high current DC supply for my mobile HF rig.
I have 4 - transformers that are all the same part number, there output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like it would
work ok, Im not sure about paralleling DC supplies ?


That should work OK. If you want a regulated supply then connect the
regulator after the combined DC
voltages. That way you don't have to be concerned with the possible
reverse current through one
of the regulator circuits.

Bill K7NOM

clc wrote:

Im still trying to come up with a high current DC supply for my mobile HF rig.
I have 4 - transformers that are all the same part number, there output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like it would
work ok, Im not sure about paralleling DC supplies ?


That should work OK. If you want a regulated supply then connect the
regulator after the combined DC
voltages. That way you don't have to be concerned with the possible
reverse current through one
of the regulator circuits.

Bill K7NOM

clc wrote:
Im still trying to come up with a high current DC supply for my mobile HF rig.
I have 4 - transformers that are all the same part number, there output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like it would
work ok, Im not sure about paralleling DC supplies ?

Why don't you connect the transformers in parallel and rectify /
stabilize the total AC current?

Hans

clc wrote:
Im still trying to come up with a high current DC supply for my mobile HF rig.
I have 4 - transformers that are all the same part number, there output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like it would
work ok, Im not sure about paralleling DC supplies ?

Why don't you connect the transformers in parallel and rectify /
stabilize the total AC current?

Hans

Paralleling DC supplies can be problematic if they are regulated supplies and
not designed for paralleling. Another solution to consider is using a deep
cycle battery and a charger. Works fine, even during a power outage...

Paralleling DC supplies can be problematic if they are regulated supplies and
not designed for paralleling. Another solution to consider is using a deep
cycle battery and a charger. Works fine, even during a power outage...

Hans wrote:

clc wrote:

Im still trying to come up with a high current DC supply for my
mobile HF rig.
I have 4 - transformers that are all the same part number, there
output is 4amp
at 18.5 vac. I want to hook a bridge to each & then connect the DC
outputs of
each in parallel to increase current to my regulator circut.
I should end up with 17 - 18 VDC @ 16 amps. Does this sound like
it would
work ok, Im not sure about paralleling DC supplies ?


Why don't you connect the transformers in parallel and rectify /
stabilize the total AC current?

Hans

There is a "chance" that the voltages won't be exactly the same. As a
result you can
have circulating currents in the transformers from that difference. The
diodes solve
that potential problem.

Bill K7NOM