Lookin for Cheap 15V Power Supply

[brianafischer]

I have the privelage to use a 15V sensor in my 480VAC/120VAC/24VDC system. The cost of purchasing a 15V supply is near $75 from here: omega.com FPW-15 $75.00 15 Vdc, 400 mA The sensor may pull up to 300mA of current and does not require signal conditioning. Is there any easy RC circuit that I could create to step down the 24VDC? Any other reccomendations for a 15V power supply? Thanks, Brian I think this may do the trick. Any warnings or other suggestions?

[forqnc]

If you are looking for Cheap, then connect Diodes in series from you 24Vdc, each Diode will drop about 0.7V so.... 24-15=9 9/0.7 is approx 13 Diodes. Hey you did ask for cheap

[panic mode]

switching power supply in the link looks fine. RC circuits would not produce regulated output without use of active components. if interested in DIY, two resistors and LM317T would do this for example but keep in mind power dissipation. (24V-15V)*0.3A=2.7W - little heatsink wouldn't hurt.

[brianafischer]

This is more of a "fun" project. I ended up ordering the switching wall supply for $12.50. Any other cool ideas? The cheaper the better! I think forqnc has the cheap prize and panic mode has the cheap but practical award...

[TimWilborne]

When my trucks running the alternator puts out 14.7 Volts. Is that close enough? If so then it would be free Do I win

[entertron]

Here are a few links from Marlin P Jones & Associates with regards to a 15 volt DC power supply: http://www.mpja.com/productview.asp?product=14510+PS http://www.mpja.com/productview.asp?product=16002+PS http://www.mpja.com/productview.asp?product=16007+PS http://www.mpja.com/productview.asp?product=16007+PS One of the problems with wall supplies is that their output is never truly predictable, while the range can vary widely. Hope this helps. God Bless,

[TERdON]

Your solution is totally adequate, I just want to add another possibility: DC/DC power supplies (voltage pumps). They are available as ICs at about $20-$40, some soldering and you'd have a nice solution. We use them regularly because we have one type of sensor which requires 5VDC, and normally we use only 3x400VAC/230VAC/24VDC...

[BobLfoot]

Glad to see ther are still a few of us old schoolers out thre. LM317 was going to be my suggestion. I've used them for a lot of custom apps and never been dissappointed, except when someone else did the soldering.

[panic mode]

well they are so cheap and we always seam to need special, stable voltage such as 10, 12, 15V or something else as needed for the application. easy solution is 317 with one resistor and one trim-pot to choose from 1.2..20V. extra resistor and LED to show when circuit is on. takes 1minute to make, flexibility is amazing and total cost about $3.

[BobLfoot]

Hey Panic have you ever added the Bypass Transistor and allowed the LM317 to drive the base for a high amperage regulated supply. Can't remember the LM # on the Xistor but it was a To 220 case and needed a heat sink. Actually took a 14 A 24 VDC and regualted it as 5V by 20A and 12V by 10A and 24V by 5A. It was fun to do.

[panic mode]

yep, but i never needed more than 4-5a. also converted them to switching mode to reduce heat...

[BobLfoot]

What can I say to that, the "Bayou Boys' of third shift often do some crazy stuff to get product out the door, but our numbers always are good. Might not be what the 8AM quarterbacks wanted called, but then they weren't there at 3AM when the machine failed either.