shane
22-10-2020, 17:56
Another victim of the impending downsize move.
A while ago, I acquired a fully built up PCB from a WAD Phono 2, and set about building casework and a PSU for it. Following conversations with the good people on Audio-Talk, I put together a shunt PSU using a circuit based on an idea by Nick Gorham, and using one of Nick de Smith's Morgan Jones-inspired statistical voltage regulators for the HT. The PSU has a 240v - 9v transformer which feeds two rectifiers in the PSU case. One feeds DC to a voltage regulator in the main case which supplies the heaters, and the other is a very simple DC supply which energises a relay which connects the secondary of the mains transformer to the secondary of another identical transformer This then outputs 240v to a rectifier, still in the PSU case. The DC from this is then fed to the regulator board in the main case. There are two umbilicals, one carries the 240v DC supply to the HT regulator, the other carries the 9V DC supply to the heater regulator, thus keeping any ripple fields from the heater supply away from the HT supply. The other 9v DC supply connects to the power switch on the main case and back through both umbilicals to the relay in the PSU case which switches on the supply to the HT transformer, thus ensuring that the power cannot be switched on unless both umbilicals are connected. There are indicator lights for the 9v relay supply, the heater supply and the HT on both cases, but the PSU case can be hidden if need be as the power switch is on the main case.
I finished this thing about 18 months ago after a protracted build period with many design changes and used it for about three months, after which life got in the way and it’s been sitting idle. It sounds beautiful, but there is a slight residual hum that I’ve never had time to track down.
I must emphasize that this is a DIY project and my assembly skills are average at best. It has dangerous voltages inside, and is not built to any sort of safety standard other than basic common sense. It needs to go to someone who fully understands valve equipment, and who is prepared to rebuild it if need be!! If it bursts into purple flames the moment it’s switched on, then so be it!
I’m asking £75, which is basically the cost of the chassis and the transformers. The rest is chucked in for nowt!
As with the KEL84, I don’t want to give this to a carrier, so collection only either from South Devon or South Somerset, or I may deliver a reasonable distance for the cost of the diesel.
More info here:http://www.audio-talk.co.uk/phpBB3/viewtopic.php?f=11&t=6809
And here: http://www.audio-talk.co.uk/phpBB3/viewtopic.php?f=11&t=6204&hilit=statistical+regulator
https://i.postimg.cc/4yt0ZHfk/p2-front-stack.jpg
https://i.postimg.cc/63FPDfNf/p2-front-ss.jpg
https://i.postimg.cc/zByMtP4f/P2-front-ss-distant.jpg
https://i.postimg.cc/CKPX4VPt/P2-top.jpg
https://i.postimg.cc/KvSVfffZ/p2-rear-stack.jpg
https://i.postimg.cc/yNY29NPc/p2-rear-ss.jpg
https://i.postimg.cc/2jBMnM4c/p2-rear-SD-distant.jpg
https://i.postimg.cc/8zw01SS5/p2-inside-p2.jpg
https://i.postimg.cc/Dw7NkzRH/p2-inside-psu.jpg
https://i.postimg.cc/0NQHjBkC/p2-inside-both.jpg
A while ago, I acquired a fully built up PCB from a WAD Phono 2, and set about building casework and a PSU for it. Following conversations with the good people on Audio-Talk, I put together a shunt PSU using a circuit based on an idea by Nick Gorham, and using one of Nick de Smith's Morgan Jones-inspired statistical voltage regulators for the HT. The PSU has a 240v - 9v transformer which feeds two rectifiers in the PSU case. One feeds DC to a voltage regulator in the main case which supplies the heaters, and the other is a very simple DC supply which energises a relay which connects the secondary of the mains transformer to the secondary of another identical transformer This then outputs 240v to a rectifier, still in the PSU case. The DC from this is then fed to the regulator board in the main case. There are two umbilicals, one carries the 240v DC supply to the HT regulator, the other carries the 9V DC supply to the heater regulator, thus keeping any ripple fields from the heater supply away from the HT supply. The other 9v DC supply connects to the power switch on the main case and back through both umbilicals to the relay in the PSU case which switches on the supply to the HT transformer, thus ensuring that the power cannot be switched on unless both umbilicals are connected. There are indicator lights for the 9v relay supply, the heater supply and the HT on both cases, but the PSU case can be hidden if need be as the power switch is on the main case.
I finished this thing about 18 months ago after a protracted build period with many design changes and used it for about three months, after which life got in the way and it’s been sitting idle. It sounds beautiful, but there is a slight residual hum that I’ve never had time to track down.
I must emphasize that this is a DIY project and my assembly skills are average at best. It has dangerous voltages inside, and is not built to any sort of safety standard other than basic common sense. It needs to go to someone who fully understands valve equipment, and who is prepared to rebuild it if need be!! If it bursts into purple flames the moment it’s switched on, then so be it!
I’m asking £75, which is basically the cost of the chassis and the transformers. The rest is chucked in for nowt!
As with the KEL84, I don’t want to give this to a carrier, so collection only either from South Devon or South Somerset, or I may deliver a reasonable distance for the cost of the diesel.
More info here:http://www.audio-talk.co.uk/phpBB3/viewtopic.php?f=11&t=6809
And here: http://www.audio-talk.co.uk/phpBB3/viewtopic.php?f=11&t=6204&hilit=statistical+regulator
https://i.postimg.cc/4yt0ZHfk/p2-front-stack.jpg
https://i.postimg.cc/63FPDfNf/p2-front-ss.jpg
https://i.postimg.cc/zByMtP4f/P2-front-ss-distant.jpg
https://i.postimg.cc/CKPX4VPt/P2-top.jpg
https://i.postimg.cc/KvSVfffZ/p2-rear-stack.jpg
https://i.postimg.cc/yNY29NPc/p2-rear-ss.jpg
https://i.postimg.cc/2jBMnM4c/p2-rear-SD-distant.jpg
https://i.postimg.cc/8zw01SS5/p2-inside-p2.jpg
https://i.postimg.cc/Dw7NkzRH/p2-inside-psu.jpg
https://i.postimg.cc/0NQHjBkC/p2-inside-both.jpg