Combining Two 12v DC PSU Outputs for 24v

[andyh747]

I have a 9 output CCTV PSU wall mounted supply. I have several spare outputs and need to run a maglock rated at 24v DC 250ma. Each output on the PSU is rated at 12v DV 2A.

Can I link two outputs in series to output 24v DC?

 

[ImpededLoop]

I imagine that all the negatives are linked (and probably the positives too), so linking two outputs in series would just cause it to go pop.

 

[andyh747]

I imagine that all the negatives are linked (and probably the positives too), so linking two outputs would just cause it to go pop.

That's what I feared might happen which is why I haven't tried it yet!
Each output is protected by it's own resettable PTC so not sure if that would offer any protection from doing any damage by trying it?

 

[ImpededLoop]

I'd buy a dedicated 24v psu. I can't see it working with the existing psu.

 

[DPG]

You could always do a continuity check (with power off) between the negatives of the DC outputs, but as above they are probably all common to each other.

 

[andyh747]

You could always do a continuity check (with power off) between the negatives of the DC outputs, but as above they are probably all common to each other.

That's great idea. I'll try that but it looks like I'll be buying a new PSU for this. I was just hoping to use the battery backup for the maglock but it's not a security issue so not essential.

 

[Zerax]

If you only want 250mA output then another option could be to use a boost converter... loads for sale on Ebay... They're not super efficient, but you've got 2A output to play with and it's mains powered, so no worries there.

 

[andyh747]

If you only want 250mA output then another option could be to use a boost converter... loads for sale on Ebay... They're not super efficient, but you've got 2A output to play with and it's mains powered, so no worries there.

Another good suggestion, many thanks. Never even thought that was an option. So would this also work on battery backup? I assume so as the input to the booster is from the output on the PSU which remains powered during battery backup. I assume this would drain the backup battery quicker though.

 

[telectrix]

another option is to search out an old fire alarm panel that a local installer has replaced and is scrapping. most have 24V PSU inside, with back up batteries. saves polar bears also.

 

[Zerax]

another option is to search out an old fire alarm panel that a local installer has replaced and is scrapping. most have 24V PSU inside, with back up batteries. saves polar bears also.

You are definitely a scouser !

 

[telectrix]

You are definitely a scouser !

and bloody proud of it. . joking aside. i'm like my dad up to a point, but i don't straighten rusty nails or make wall plugs out of bits of scrap wood like he did. he even made his own buckle clips from tin cans, cut out with snips.