Rafa you would be correct if those actually were "ideal diodes" that the professor talks about in the first few weeks of Circuit Design 101. However, real diodes like the ones inside the GBJ2506 are not ideal.
In particular, the diodes inside GBJ2506 have a "forward voltage" ... they don't conduct current until Vanode > Vcathode + VFWD. For silicon diodes like these, VFWD is in the neighborhood of 0.6V.
So the bridge only conducts current when either
5V_COLD > CHASSIS_STAR_PE + 0.6
or
5V_COLD < CHASSIS_STAR_PE - 0.6
In other words, when 5V_COLD is "noticeably different" from mains protective earth. For example, when the little SMPS module develops an internal fault that shorts 5V_COLD to the live mains. In that case there's a 25 ampere diode (a pair of them in parallel, as you point out!) connecting that current straight to mains protective earth. Protecting anything or anyone that touches 5V_COLD. Including the front panel on/off switch.
In particular, the diodes inside GBJ2506 have a "forward voltage" ... they don't conduct current until Vanode > Vcathode + VFWD. For silicon diodes like these, VFWD is in the neighborhood of 0.6V.
Ideal diode: conducts when Vanode > Vcathode + 0
Silicon diode: conducts when Vanode > Vcathode + approx. 0.6V
Silicon diode: conducts when Vanode > Vcathode + approx. 0.6V
So the bridge only conducts current when either
5V_COLD > CHASSIS_STAR_PE + 0.6
or
5V_COLD < CHASSIS_STAR_PE - 0.6
In other words, when 5V_COLD is "noticeably different" from mains protective earth. For example, when the little SMPS module develops an internal fault that shorts 5V_COLD to the live mains. In that case there's a 25 ampere diode (a pair of them in parallel, as you point out!) connecting that current straight to mains protective earth. Protecting anything or anyone that touches 5V_COLD. Including the front panel on/off switch.
Anti vandal switch wiring?
Good afternoon all..
I've built two of these boards and have tested both.. Both working as expected so far. I'll be using one in Salas DCG3, and one later in my Aleph J.
I ordered a latching push button with LED from AliExpress to use on my DCG3. I"m mostly certain I have wired the switch improperly and this application is not very well documented on the tech portion of the AliExpress product page.
Seems to be working however it's powering "On" with the button out, and "OFF" with the button "IN" which is opposite from what I'd expect (and not what a similar switch on my WHAMMY) does..
Product Page: https://www.aliexpress.com/item/1005002610826549.html?spm=a2g0s.9042311.0.0.451e4c4dJtbNm5
My switch has this rear connector:
I currently have it wired to power board "Switch" at the NC and C.. and the "LED on" at power board to the two left and right terminals on the back of the switch pictured above.. Thanks for any suggestions.. Hate to blow the LED or fry myself! lol..
Good afternoon all..
I've built two of these boards and have tested both.. Both working as expected so far. I'll be using one in Salas DCG3, and one later in my Aleph J.
I ordered a latching push button with LED from AliExpress to use on my DCG3. I"m mostly certain I have wired the switch improperly and this application is not very well documented on the tech portion of the AliExpress product page.
Seems to be working however it's powering "On" with the button out, and "OFF" with the button "IN" which is opposite from what I'd expect (and not what a similar switch on my WHAMMY) does..
Product Page: https://www.aliexpress.com/item/1005002610826549.html?spm=a2g0s.9042311.0.0.451e4c4dJtbNm5
My switch has this rear connector:
I currently have it wired to power board "Switch" at the NC and C.. and the "LED on" at power board to the two left and right terminals on the back of the switch pictured above.. Thanks for any suggestions.. Hate to blow the LED or fry myself! lol..
"When in doubt -- buzz it out!"
Meaning: don't trust the documentation until after you verify it yourself on the real thing. Use the continuity tester ("buzzer") feature of your multimeter to find a pair of I/O terminals on the switch, I'll call them "Bob" and "Alice", with these features:
Meaning: don't trust the documentation until after you verify it yourself on the real thing. Use the continuity tester ("buzzer") feature of your multimeter to find a pair of I/O terminals on the switch, I'll call them "Bob" and "Alice", with these features:
- When button is not pushed, no continuity between Bob and Alice
- When button IS pushed, yes there is continuity between Bob and Alice
Kevin! Thank you.. Super simple solution.. Foolishly, I didn't know what NC and NO stood for.. (I'm learning very slowly!)
Mark.. Thanks very much! I actually did 'beep out' the terminals (I should say I attempted to but missed that inner post check between Bob and Alice!).. Lol..What is the saying, "close only counts in horseshoes and hand grenades".. The LED portion, I assumed would be the two outer terminals and I actually connected the leads from the LED terminals to my Mega tester to see if it would tell me which side of the diode was +/- and it deduced that the diode was a capacitor.. Hmm.. Will do some reading on using the multi meter to determine which was which.. The LED did illuminate when I tested the switch, I probably got lucky..
Thank you again!
Before I order a batch of PCBs from a fabricator I thought I would ask if anyone has one spare that they can sell ? I'm in the UK - I imagine a single PCB will be fairly cheap to ship and probably slip past the import tax racketeers.
I'll order from a fabricator if nothing turns up by the end of the week.
I'll order from a fabricator if nothing turns up by the end of the week.
Click on the link in post #3, it will fill up a Mouser shopping cart with "all parts" for this project (assuming member pfarrell made no errors and usually he does not). Change your country/currency as needed and scroll down to the bottom to see the grand total.
@nautibuoy did you order pcbs? I was about to if you wanted any.
I think I will order the dip14 ics direct from Ti as they are cheaper than Mouser and all in stock. I looked into using the soic versions with an adaptor board but couldn't find anything suitable.
The smps is available from a few resellers in the UK but nearer to £15 than £5
I think I will order the dip14 ics direct from Ti as they are cheaper than Mouser and all in stock. I looked into using the soic versions with an adaptor board but couldn't find anything suitable.
The smps is available from a few resellers in the UK but nearer to £15 than £5
Hi Jim. Thanks for asking.
Coincidentally, I was planning to contact you as the heatsink to replace the one you loaned me has just arrived
I did have a tentative offer but I didn't get a reply to my PM so I still need some and it would be good to pitch in with you and share the costs - I have a current need to two but if it makes it easier some extras will be handy at some point I expect. I would also be interested in a couple of sets of the ICs if that works for you?
Ray
Coincidentally, I was planning to contact you as the heatsink to replace the one you loaned me has just arrived
I did have a tentative offer but I didn't get a reply to my PM so I still need some and it would be good to pitch in with you and share the costs - I have a current need to two but if it makes it easier some extras will be handy at some point I expect. I would also be interested in a couple of sets of the ICs if that works for you?
Ray
I'll order 10 boards. I only need a couple. I've put 10 each of the ICs in the basket but I might up it. They're 35p each. Postage is only a fiver from Ti.
Just sussing out the optocoupler thing. The through hole are out of stock. The smd ones just seem to have had they're legs chopped off!
Just sussing out the optocoupler thing. The through hole are out of stock. The smd ones just seem to have had they're legs chopped off!
Hi, I took the liberty to check the circuit with regards to the power reduction of the relay coil as in thread: https://www.diyaudio.com/forums/power-supplies/375451-pcb-push-push-mains-switch-12.html#post6781088
With RTD14005 the coil resistance is 62 Ohm. R12 is also 62 Ohms. The release voltage is only 0.5V but...the coil diagrams show that using the relays below 0.9 x rated coil voltage is not recommended. Unfortunately no minimum holding current is specified. That means 4.5V as a minimum for the 5V version of the relay. Below that voltage the contact pressure of the contacts is lower and contacts may burn in. Since there is no clear data of this type with regards to the relation of contact lifetime and lower coil voltage it is a strong assumption based on other relays and experience. Seen from the other angle: one can only rely on the numbers with the coil voltage as specified. Reduction of the 400 mW of consumed power can be done by choosing a type with for instance 200 mW power consumption and the same current ratings. There is no real gain in reducing power considering the meagre 0.4W and the limited hours per day it is energized and it makes contact life uncertain probably reducing the lifetime of the relay.
In simple language: a 5V relay is meant to be used with 5V +/- x% for rated current of the contacts. Please review/research.
https://www.mouser.de/datasheet/2/418/5/ENG_DS_RT1_1120-729126.pdf
With RTD14005 the coil resistance is 62 Ohm. R12 is also 62 Ohms. The release voltage is only 0.5V but...the coil diagrams show that using the relays below 0.9 x rated coil voltage is not recommended. Unfortunately no minimum holding current is specified. That means 4.5V as a minimum for the 5V version of the relay. Below that voltage the contact pressure of the contacts is lower and contacts may burn in. Since there is no clear data of this type with regards to the relation of contact lifetime and lower coil voltage it is a strong assumption based on other relays and experience. Seen from the other angle: one can only rely on the numbers with the coil voltage as specified. Reduction of the 400 mW of consumed power can be done by choosing a type with for instance 200 mW power consumption and the same current ratings. There is no real gain in reducing power considering the meagre 0.4W and the limited hours per day it is energized and it makes contact life uncertain probably reducing the lifetime of the relay.
In simple language: a 5V relay is meant to be used with 5V +/- x% for rated current of the contacts. Please review/research.
https://www.mouser.de/datasheet/2/418/5/ENG_DS_RT1_1120-729126.pdf
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