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DIY Workshop » ε24: Power switch driver circuit | fault151 Member Joined: Dec. 10, 2007 |  Message [#200] posted on: 01-29-2009 08:38 AM CST (US).   |  |  HI Ti, i managed to have a look at the different ones. Theres quite a few. Theres a 13va version 7.5 version 4.5 version and a 2va version I just need to check that the physical size is the same as your o24 board. Would the mid ranged 7.5va version be the most suited? Thank you |
amb  Headphone Council Joined: Apr. 1, 2004 | Message [#201] posted on: 01-29-2009 01:03 PM CST (US). | | I would think that the 4.5VA version (which is 3x the rating of your current one) should be good enough. While using a higher rating won't hurt in this case, the bigger transformer would emit more EMI. Definitely check the size and the pin-out compatibility with the σ24, as well as height (for fitment in your case). |
| fault151 Member Joined: Dec. 10, 2007 | Message [#202] posted on: 01-29-2009 01:07 PM CST (US). | | ok cool, i will be fine for height of case as its way off the lid. Its the pins that could be a problem. I'll have a look and order one at some point. My jfets i ordered arrived from you yesterday so i can install them in the meantime. Gives me something to do. I hope it cures the problem i was having. Thank you |
| fault151 Member Joined: Dec. 10, 2007 | Message [#203] posted on: 01-29-2009 03:57 PM CST (US). | | Just been looking at the measurements for the transformers. I don't think i am going to be able to use the 024 board with the either of the bigger versions of the transformer. The pins are wider apart. Do you think it would be possible to be able to mount one on a board and wire the underneath and use connector blocks my self to create a diy version of the o24 board? Id prefer to use a pcb mount transformer as it looks a bit neater. |
| fault151 Member Joined: Dec. 10, 2007 | Message [#204] posted on: 01-29-2009 04:01 PM CST (US). | | When you designed the 024 board was it not for the exact transformer i have,to power the e24? I'm just wondering why the 024 is the size it is? I can't find one that is the same foot print as your 024 but more powerful. |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#205] posted on: 01-29-2009 05:12 PM CST (US). | |
The σ24 board was designed to accommodate "EI-30" standard footprint transformers, but depending on the manufacturer, they make transformers in this footprint (or not) with different electrical specifications. It is up to you to find one that works. |
| fault151 Member Joined: Dec. 10, 2007 | Message [#206] posted on: 01-30-2009 02:18 PM CST (US). | | I'll see what other manufacturers have them in the same size with more power. If not i'll have to try put them on my own board and wire them my self. |
| digger945 Member Joined: Oct. 1, 2008 | Message [#207] posted on: 02-18-2009 07:13 PM CST (US). | | Is R3 the resistor you change to match your LED? I have the Lamptron black vandal switch from performancepc.com with a green LED ring(I guess it's a green led, the switch I ordered is with the green ring). The packaging and info supplied with the switch both have an led rating of 20mA but 4 different forward voltages(1.85, 2.3, 3.5, and 3.6V on the package, 3.4V on the instructions). I really don't want to burn up a $25 switch, and the LED resistor calculator I use is suggesting 560ohms for a supply of 12V. |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#208] posted on: 02-18-2009 09:42 PM CST (US). | | digger945, yes, R3 is the LED current limit resistor. The default of 2.2K should be a very safe value for any LED, because it will allow no more than about 3.6mA-4.6mA through the LED (actual current depends on the LED's forward voltage, this range spans an LED forward voltage of 1.7V-4V). For most LEDs the default resistance should achieve adequate brightness. Your switch LED rating of 20mA is a maximum that you should never exceed, and it is not what the LED should operate at. If you find that the LED is too dim, then consider reducing R3's value. |
| digger945 Member Joined: Oct. 1, 2008 | Message [#209] posted on: 02-19-2009 04:22 PM CST (US). | | Thank Ti, I already have your pcb and all the parts per your BOM. I think I'll stick with that and see how it goes. The switch I have is identical to the Bulgin, it's just plastic instead of stainless. BTW, this will be switching a Teledyne SS relay for 2 Sigma22's. [Edited by digger945 on 02-19-2009 at 05:26 PM.] |
| MrMajestic2 Member Joined: Jun. 5, 2007 | Message [#210] posted on: 03-17-2009 01:23 PM CST (US). | | Whats the minimum rating for the vandal switch. I have one that is rated at 12V/20A. |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#211] posted on: 03-17-2009 01:56 PM CST (US). | |
I recommend a switch rated at least 12V. Little current will flow through the switch (milliamps), so your switch is much more than adequate. |
| MrMajestic2 Member Joined: Jun. 5, 2007 | Message [#212] posted on: 03-17-2009 02:12 PM CST (US). | |
Great, thanks. |
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