I am designing a setup that requires 24 separately controlled 130W heaters. The "heaters" are constructed from silicone-insulated resistance cable and I'd prefer to keep it low voltage as I'll be building it myself. So far I have controlled each heater via a FET switched from a Picaxe chip on a 1-second PWM duty cycle. So I need about 3000W of 12v supply (or possibly 18 or 24v). So, say ten 400W supplies may be obtained.
The cheapest local choice seems to be computer ATX power supplies like this 500W one
http://www.ascent.co.nz/productspecification.aspx?ItemID=415767 for about US$50
One would have thought "plain" switch mode PS would be cheaper but in our market even a 150W unit from Jaycar is US$84 and higher power ones if available are even dearer.
http://www.ascent.co.nz/productspecification.aspx?ItemID=415767
Aliexpress from China shows much cheaper switch mode single voltage units like this 400W one for US$40 shipped
http://www.aliexpress.com/item/S-40...nic-LED-Transformer-AC-DC-CNC/1971159120.html
So what is my question...?
1. For my purpose are there pros and cons of bottom-end ATX supplies vs "plain" switch mode power supplies?
2. For either power source is a problem created by the power demand flicking on and off all the time? (As 3 - 4 heaters would be controlled from each PS I'd try to stagger the PWM pulses to be out of phase).
I understand that using the non-ATX units gives me choices of 18 or 24v which may be advantageous in choosing resistance ratings and reducing currents (I have heard of linking ATX supplies to give 24v but am not keen on that).
regards
Nelson
PS (excuse the pun) I'd be happy to use simple wire-wound transformers and rectify etc but they are even dearer for that power, and would be heavy to import from China.
The cheapest local choice seems to be computer ATX power supplies like this 500W one
http://www.ascent.co.nz/productspecification.aspx?ItemID=415767 for about US$50
One would have thought "plain" switch mode PS would be cheaper but in our market even a 150W unit from Jaycar is US$84 and higher power ones if available are even dearer.
http://www.ascent.co.nz/productspecification.aspx?ItemID=415767
Aliexpress from China shows much cheaper switch mode single voltage units like this 400W one for US$40 shipped
http://www.aliexpress.com/item/S-40...nic-LED-Transformer-AC-DC-CNC/1971159120.html
So what is my question...?
1. For my purpose are there pros and cons of bottom-end ATX supplies vs "plain" switch mode power supplies?
2. For either power source is a problem created by the power demand flicking on and off all the time? (As 3 - 4 heaters would be controlled from each PS I'd try to stagger the PWM pulses to be out of phase).
I understand that using the non-ATX units gives me choices of 18 or 24v which may be advantageous in choosing resistance ratings and reducing currents (I have heard of linking ATX supplies to give 24v but am not keen on that).
regards
Nelson
PS (excuse the pun) I'd be happy to use simple wire-wound transformers and rectify etc but they are even dearer for that power, and would be heavy to import from China.