The ways of the TH-cam algorithm are mysterious, obscure and verily most perplexing. Now you've found the Knights of The Thermionic Valve after three days of hideous torture you'll be given the password & a copy of the Big Red Book. Welcome Brother. : )
I sometimes used a slow-heating kenotron (rectifier or booster diode) such as PY88 as a delay element, with a relay coil in line with the plate. If a bias supply is beefy enough, it can handle the heater and plate current. Otherwise use EY88, 6D22S or other 6.3V heated one, and use the bias supply for plate/relay only.
Thanks for your IP. Not come across the term Kenotron before, though I know some of the lads over on DIYaudio use TV damper diodes for a similar application, they're harder to get here in the UK though. Also familiar with using the bias to activate a slow start circuit. To be honest though a soft/slow start circuit is a bit of a faff, something else to go wrong. Different ways of skinning a cat. The reason I used it in this amp & others is to give the caps an easier life whilst the valves start to conduct fully. TFW & hope you find these video's useful or whatever.
Hi Andy, having had my fair share of delay start demons to deal with as you know, I’m glad you managed to sort it in the end. Looking forward to the sound test through your big speakers ! : ) Your bike sounds great as well! : )
I saw your scope probe was still set to 1x. Set it to 10x! The 10x mode has much lower capacitance and is safer to use for these applications. If your Darlington pairs transistors aren't low enough Vbe you could build a discrete Sziklai pair.
Well spotted. I used the 1x because the amplitude was small, my scopes lowest setting is 50mV P-P/div unless I switch it onto 10x gain. It's an old scope & temperamental at hi gain. Again your right, there's better circuits I could use, in this case I wanted a quick solution using what parts I had. TFW.
@@diabolicalartificer The 10x mode on your scope should only be changing the way the numbers are reflected unless you're using an analog scope :) The lower capacitance of the 10x mode is significant when you're working with tubes, because the capacitance of the probe can actually significantly change the behaviour of some very low current high voltage tube circuits.
Can't wait until you get the bike fully going. It's been a long haul on it. Odd that the amp was working fine them the diode failed. Chineseium part? I've been had by counterfeit parts off one site by a certain seller.
Me too, it's nearly been 3 years. I think the amp started playing up because of all the frequent powering on &off with relatively short times between each. The diodes are NOS BYW56C I think, 1000v 1A Avalanche power rectification diodes. I try to limit my purchases the best I can from the PRC. Futile probably but.
@@diabolicalartificer The venerable classic 1N4007 is a fine replacement for a rectifier that needs to do 1 A at 1000 V. They aren't suitable for high frequency rectification, but mains frequency is well within its capacity. The BYW56C is *not* a 1 A diode though! It's a 2 A diode. The RL207 is a part I frequently use these days, as it's far cheaper than the older alternatives that are high power silicon rectifier diodes. It *is* rated for 2 A operation. The older one I used to stock was the 1N5408, and you may actually have some in stock if you've got any parts from anywhere.
@@AnnaVannieuwenhuyse Again, your right, I'm getting on in years, my brain is a bit buggered, I make frequent mistakes & chuck these video's together. You know your stuff, thanks for the tips.
@@diabolicalartificer All good mate! You do you :) I would've felt guilty not correcting a small factual error that could cause you to choose the wrong part :O
I have no idea why it's taken youtube so long to offer me one of your videos in my feed, but here we are.
The ways of the TH-cam algorithm are mysterious, obscure and verily most perplexing. Now you've found the Knights of The Thermionic Valve after three days of hideous torture you'll be given the password & a copy of the Big Red Book. Welcome Brother. : )
I sometimes used a slow-heating kenotron (rectifier or booster diode) such as PY88 as a delay element, with a relay coil in line with the plate. If a bias supply is beefy enough, it can handle the heater and plate current. Otherwise use EY88, 6D22S or other 6.3V heated one, and use the bias supply for plate/relay only.
Thanks for your IP. Not come across the term Kenotron before, though I know some of the lads over on DIYaudio use TV damper diodes for a similar application, they're harder to get here in the UK though. Also familiar with using the bias to activate a slow start circuit. To be honest though a soft/slow start circuit is a bit of a faff, something else to go wrong. Different ways of skinning a cat. The reason I used it in this amp & others is to give the caps an easier life whilst the valves start to conduct fully. TFW & hope you find these video's useful or whatever.
Hi Andy, having had my fair share of delay start demons to deal with as you know, I’m glad you managed to sort it in the end.
Looking forward to the sound test through your big speakers ! : )
Your bike sounds great as well! : )
Aye, it's been an interesting week, got there in the end. TFW
Another good video. Cheers! Liked the bike and tank artwork too. ATB Adam
Thank you. Though the paint finish isn't 100%, I'm happy with how the tank turned out. TFW, take care.
fun stuff building valve amps and goodies
Sometimes fun, sometimes maddening. That said it's more interesting when things go wrong. TFW.
I saw your scope probe was still set to 1x. Set it to 10x! The 10x mode has much lower capacitance and is safer to use for these applications.
If your Darlington pairs transistors aren't low enough Vbe you could build a discrete Sziklai pair.
Well spotted. I used the 1x because the amplitude was small, my scopes lowest setting is 50mV P-P/div unless I switch it onto 10x gain. It's an old scope & temperamental at hi gain. Again your right, there's better circuits I could use, in this case I wanted a quick solution using what parts I had. TFW.
@@diabolicalartificer The 10x mode on your scope should only be changing the way the numbers are reflected unless you're using an analog scope :)
The lower capacitance of the 10x mode is significant when you're working with tubes, because the capacitance of the probe can actually significantly change the behaviour of some very low current high voltage tube circuits.
Identifies as a Foden - obviously a Mr Hewes follower like myself!
Excellent, your the first one to spot that. I slip little bits into my video's, obscure music lyrics etc. TFW.
Can't wait until you get the bike fully going. It's been a long haul on it. Odd that the amp was working fine them the diode failed. Chineseium part? I've been had by counterfeit parts off one site by a certain seller.
Me too, it's nearly been 3 years. I think the amp started playing up because of all the frequent powering on &off with relatively short times between each. The diodes are NOS BYW56C I think, 1000v 1A Avalanche power rectification diodes. I try to limit my purchases the best I can from the PRC. Futile probably but.
@@diabolicalartificer The venerable classic 1N4007 is a fine replacement for a rectifier that needs to do 1 A at 1000 V. They aren't suitable for high frequency rectification, but mains frequency is well within its capacity.
The BYW56C is *not* a 1 A diode though! It's a 2 A diode. The RL207 is a part I frequently use these days, as it's far cheaper than the older alternatives that are high power silicon rectifier diodes. It *is* rated for 2 A operation. The older one I used to stock was the 1N5408, and you may actually have some in stock if you've got any parts from anywhere.
@@AnnaVannieuwenhuyse Again, your right, I'm getting on in years, my brain is a bit buggered, I make frequent mistakes & chuck these video's together. You know your stuff, thanks for the tips.
@@diabolicalartificer All good mate! You do you :) I would've felt guilty not correcting a small factual error that could cause you to choose the wrong part :O
what a strange thumbnail… 🫢
Aye, looks like a hide the lightbulb pixie has been caught on camera. Now where's that damn lightbulb? TFW # 1 Daughter.
@@diabolicalartificerwatched the video, I see you’ve exposed a bit of leg 😳 views are going to go up tenfolds after this exposure
@@mollyeaw Good news, I've put my legs away, got fed up with the women banging on the door begging to see my knees.
😂
Yeah lol ❤