Yup quite right. Plenty midnight oil going to be burnt on another monster, with the slide-rule stuff completed. Again a 150+150W project using 2x quads EH KT90's with a 800W switched mode power supplies on the late night menu. A new slam driver circuitry been tested with sections ready to start the point to point.
I promised MJ with the main amp circuit diagram and this is just about completed. The prototype botch gave astoundingly good results.
The o/p trannies by Sowter UK.
richy
I promised MJ with the main amp circuit diagram and this is just about completed. The prototype botch gave astoundingly good results.
The o/p trannies by Sowter UK.
richy
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The best part is the slide rule. I still use one. Slide rules have a thinking process that requires logical organization that leads to understanding.
DT
All just for fun!
Since I sold last tube amp in the house I am going to resurrect my Tower. I built it's last version in class A+C, now going to rewire this one to pure class A like previous room heaters.
What is the Tower? sound intriquing.
I've never used a slide rule, but use to teach creativity at MTU and getting off the computer and doing something with your hands and mind always always leads to more creativity. One of these days I will take a class on how to use a slide rule....sounds like fun.
One of the things seriously lacking in todays society.....the ability to tackle and solve problems in ones head rather than use the calculator as a short cut. Fine, the calculator can crunch numbers at speed but playing bridge and correct bidding is another good persuit. All reduce Age Dementia and cell wastage.
The trick with a slide-rule is remember in ones kernel where the decimal point is.
Keep at it...Without it in 1967,there would be no moon landings.
A good Pickett slide-rule can set one back $50-$100.
Drinking wine & booze and using a slide rule will create mass errors.
MJ take note !
richy
Hello Richy,
I started home brewing as we used to call it amature radio transmitters in my earliest days of electronics 40+ years ago and made some fine bird nests too. We only took it one step further in the early days, once the bird's nest was complete, we then tuned for maximum smoke. Kind of reminds me of Tubelab's saying "Too much power is almost enough! Turn it up till it explodes - then back up just a little". . This comes close to describing how hard we would push the output power.
Mickeystan
Birds nesting hint:- The best component for assessing the value of the phase compens Zobel cap often found in the 1st anode stage of tube amps is to use an old air spaced 30-500pF variable tuning cap (in pic) often found in early AM radio stuff. Use with case grounded and series connected to a variable pot connected to the anode. Never dump these caps. They are mighty useful. If one has two, the other one can be put in the global nfb path, then one is in a good position to optimise all variables for good looking square waves and top end thd. Disconnect and measure the cap with an RCL meter.
Once one has mastered this trick, it becomes short work to attain values required for excellent HF stability in any amp.
In general I find the calculated values in such Zobel circuits quite a way out (often 20%), due to layout strays,unknown Miller effects and worst of all the output tranny characteristics.
richy
Once one has mastered this trick, it becomes short work to attain values required for excellent HF stability in any amp.
In general I find the calculated values in such Zobel circuits quite a way out (often 20%), due to layout strays,unknown Miller effects and worst of all the output tranny characteristics.
richy
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Another job for those warm weather months before the winter sets in, is the fiddly finger job of reworking/winding old power transformers.
The one in photo :-a 1kW lump from a discarded accumulator charger from a British Rail Mark1 1950's railway carrriage makes a nice mains tranny and can be conservately derated for the project.
Over time the windings have been attacked by battery fumes, so the iron makes a convenient start for the mains end of the 150+150W project. Notice the all important flat steel plinth for creating lamination flatness on assembly. The new phenol hard paper coil former has been made and temporarily set with araldite. The thin shims on top give the coil former some tolerance within the E&I when all is assembled.
After the laminations cleaned of old varnish and dirt, next, with the available winding window, rough calculations assessing current density,wire size, working flux density, acceptable winding losses and fit have to be made.
The orig winding to the right had no former cheeks, windings wound on varnished paper with no creepage. Such were the standards of yesteryear.
richy
The one in photo :-a 1kW lump from a discarded accumulator charger from a British Rail Mark1 1950's railway carrriage makes a nice mains tranny and can be conservately derated for the project.
Over time the windings have been attacked by battery fumes, so the iron makes a convenient start for the mains end of the 150+150W project. Notice the all important flat steel plinth for creating lamination flatness on assembly. The new phenol hard paper coil former has been made and temporarily set with araldite. The thin shims on top give the coil former some tolerance within the E&I when all is assembled.
After the laminations cleaned of old varnish and dirt, next, with the available winding window, rough calculations assessing current density,wire size, working flux density, acceptable winding losses and fit have to be made.
The orig winding to the right had no former cheeks, windings wound on varnished paper with no creepage. Such were the standards of yesteryear.
richy
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Yep, I agree Richy. I was a radar tech in the Navy from 73 to 77. All that mil spec gear was pretty tiddy, but the votages??? kill ya in a heart beat.
Hello,
A birds' nest need not be 850 volts. I built several Robert Pease style Op-Amp creations with the Op-Amps epoxied upside down to the copper clad ground plane. Those first projects were preamps with tone controls and active crossovers for Tri-Amp speakers and sub woofer. Could not be more fun. First projects should be low voltage birds nests.
DT
Alljust for fun!
Robert Pease NS still going ? Oh boy, this was real intuitive opamp stuff in the 1970,80's analogue hayday one never missed. I remember it too well. Spare time lash ups, resulted in loads of working projects still in the junk box.
richy
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