Use for the Tesla Switch

[John_K]

check this out
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or try it in german
Aluminium Kühlkörper mit 3 Leistungstransistoren RT (aukcja 270593011461) - aukcje eBay.pl | Zakupy bez granic!

http://cgi.ebay.at/Aluminium-Kuehlko...-/270572339992

Hey Vissie,

Nice find Have you contacted the guy to see if he still has them? You might have found yourself a couple of 108's!

Oh yeah, gotta love the Aussie humour with the matchbox in the photos

I guess now that we have found a few pics (and maybe some sub parts), we can search the globe for more


John K.

[nvisser]

I will leave it to you or Matt

[John_K]

I will leave it to you or Matt

I've emailed the guy in Sydney to see if he has any. My German is rubbish and I couldn't get translate to work to send him a message.

Can someone who speaks German contact him to see if the item is still available?


John K.

[SeaMonkey]

The only advantage the Germanium family of transistors afforded was their very low Vce in 'saturation.' This characteristic meant that while in 'saturation' their ohmic resistance from Collector to Emitter was quite low - lower than Silicon transistors during the early years of their development.

Today's Silicon transistor is very much different and a large number of them are available with Low Vce (sat) characteristics which make them similar to the older Germanium transistors with low saturation resistance collector to emitter.

Virtually any of the modern low voltage Silicon switching transistors will provide excellent saturation performance in high current switching applications up to 50 Ampere pulses.

For the absolute "best" performance, with lowest losses, then a MosFet must be used with an appropriate Driver chip. There are several MosFet Driver chips designed for Synchronous Switching Supply applications which are capable of driving N Channel MosFets in the "Tesla Switch" configuration.

There is nothing 'magical' about the old Germanium transistors.

In fact, their dis-advantages (excessive leakage, thermal runaway) make them poor choices for the kind of circuitry you are attempting to replicate.

[John_K]

The only advantage the Germanium family of transistors afforded was their very low Vce in 'saturation.' This characteristic meant that while in 'saturation' their ohmic resistance from Collector to Emitter was quite low - lower than Silicon transistors during the early years of their development.

Today's Silicon transistor is very much different and a large number of them are available with Low Vce (sat) characteristics which make them similar to the older Germanium transistors with low saturation resistance collector to emitter.

Virtually any of the modern low voltage Silicon switching transistors will provide excellent saturation performance in high current switching applications up to 50 Ampere pulses.

For the absolute "best" performance, with lowest losses, then a MosFet must be used with an appropriate Driver chip. There are several MosFet Driver chips designed for Synchronous Switching Supply applications which are capable of driving N Channel MosFets in the "Tesla Switch" configuration.

There is nothing 'magical' about the old Germanium transistors.

In fact, their dis-advantages (excessive leakage, thermal runaway) make them poor choices for the kind of circuitry you are attempting to replicate.

Thanks for the info SeaMonkey.

There may be nothing 'magical' about these transistors, but when we are attempting to replicate a device we need to try and use the exact parts that the original device used first.

How do you know that this particular transistor is a poor choice? Have you replicated the device using this transistor?

Once we have a successful replication, then we can try to substitute other parts to see if they work and so others don't have to trawl through Google and eBay for hours like we are.


John K.

[theremart]

Easy find..

Matt,

I found a site with some pictures of 108's. Looks like they were also used in IBM System/360 power supplies, which should be easier to source (???)

The System/360 Power suppy restoration project

Good luck!


John K.

--------------

EASY to find :-)

IBM xSeries 360 Hot Swap Power Supply 31P6108 00N7708 - eBay (item 310180708877 end time Aug-06-10 14:37:48 PDT)

[Matthew Jones]

The only advantage the Germanium family of transistors afforded was their very low Vce in 'saturation.' This characteristic meant that while in 'saturation' their ohmic resistance from Collector to Emitter was quite low - lower than Silicon transistors during the early years of their development.

Today's Silicon transistor is very much different and a large number of them are available with Low Vce (sat) characteristics which make them similar to the older Germanium transistors with low saturation resistance collector to emitter.

Virtually any of the modern low voltage Silicon switching transistors will provide excellent saturation performance in high current switching applications up to 50 Ampere pulses.

For the absolute "best" performance, with lowest losses, then a MosFet must be used with an appropriate Driver chip. There are several MosFet Driver chips designed for Synchronous Switching Supply applications which are capable of driving N Channel MosFets in the "Tesla Switch" configuration.

There is nothing 'magical' about the old Germanium transistors.

In fact, their dis-advantages (excessive leakage, thermal runaway) make them poor choices for the kind of circuitry you are attempting to replicate.

Then again you really wouldn't know if they were anything special unless of course you tried them. Like John said we are looking to see if they make the difference.
There have been transistors in the past that were run of the mill and performed out of expectation.

Do a little home work. This is a big thread we are very aware of what we are trying to do. Then start building.

Matt

[Matthew Jones]

--------------
EASY to find :-)
IBM xSeries 360 Hot Swap Power Supply 31P6108 00N7708 - eBay (item 310180708877 end time Aug-06-10 14:37:48 PDT)

You think thats the same thing? As Vissie's rebuild pictures?

I guess I could write the guy.

Cheers
Matt

[John_K]

You think thats the same thing? As Vissie's rebuild pictures?

I guess I could write the guy.

Cheers
Matt

Grrr, I just posted a reply to Mart but lost in the Aether...

No, they are different by about 40 years. IBM just recycled the name of the xSeries 360 to trick us into thinking it was a System/360.

Thanks for trying Mart


John K.

[Matthew Jones]

I wrote the guy and asked him about the 108's, or if he knew where some might be.

Also got a buddy mine in Germany to write that other ebay guy in german to find out if they were still for sale or if he had anymore or might know whre more are.

Matt

[SeaMonkey]

Even within a given 'type' of transistor there are large variations in the Current Gain from unit to unit. These variations in 'Beta' make part-for-part replication still a stab in the dark in many cases.

When one is aware of the principles involved in any particular 'replication' then one is able to make adjustments in the circuit parameters in order to compensate for device (transistor) deficiencies. Often times, using a Darlington pair in place of a single transistor is enough to provide the 'boost' that a deficient transistor - still within mfr. specs.- needs in order to make the 'replication' work.

Yes, it is possible to use 'silicon' in place of 'germanium' in virtually every application. In every case, the 'silicon' replication will work substantially better than the 'germanium' version.

One shortfall of the mechanical 'Tesla Switch' is 'contact arcing' when switching under normal load. By delaying load current 'pulsing' until all mechanical switches are in place and making contact, this problem can be obviated. With properly sequenced electro-mechanical relays and a 'synchronized' load current pulse, the complexity and losses of the 'transistorized' Tesla Switch can be overcome while easily eliminating the arcing at the contacts. This is a very easily accomplished enhancement of the basic 'Tesla Switch' which can be done with Silicon.

There are cases where the electro-mechanical relay may yet be the simpler and more effective solution. With a little 'creative help' from a Silicon semiconductor.

It is rather easy to get 'stuck in a rut' when one attempts to 'replicate' without fully understanding what is being 'replicated.'

[John_K]

Even within a given 'type' of transistor there are large variations in the Current Gain from unit to unit. These variations in 'Beta' make part-for-part replication still a stab in the dark in many cases.

When one is aware of the principles involved in any particular 'replication' then one is able to make adjustments in the circuit parameters in order to compensate for device (transistor) deficiencies. Often times, using a Darlington pair in place of a single transistor is enough to provide the 'boost' that a deficient transistor - still within mfr. specs.- needs in order to make the 'replication' work.

Yes, it is possible to use 'silicon' in place of 'germanium' in virtually every application. In every case, the 'silicon' replication will work substantially better than the 'germanium' version.

One shortfall of the mechanical 'Tesla Switch' is 'contact arcing' when switching under normal load. By delaying load current 'pulsing' until all mechanical switches are in place and making contact, this problem can be obviated. With properly sequenced electro-mechanical relays and a 'synchronized' load current pulse, the complexity and losses of the 'transistorized' Tesla Switch can be overcome while easily eliminating the arcing at the contacts. This is a very easily accomplished enhancement of the basic 'Tesla Switch' which can be done with Silicon.

There are cases where the electro-mechanical relay may yet be the simpler and more effective solution. With a little 'creative help' from a Silicon semiconductor.

It is rather easy to get 'stuck in a rut' when one attempts to 'replicate' without fully understanding what is being 'replicated.'

SeaMonkey,

Thanks for sharing your ideas. Please follow through with them and build what you think will work and share the results with us.

I don't think there is anyone here 'stuck in a rut' and the folks that have been around for a while have a good understanding of what we are trying to replicate.

We're just trying to bake the cake by following the recipe as so far no one has been able to successfully replicate it any other way so far. Remember that we are attempting to replicate Bill & Ray's scalar charger with the 108's, not use them for the TS.

The circuit is fairly simple, but using other types of switching (mechanical or silicon) has not produced the results we are looking for.


John K.

[SeaMonkey]

The 'Scalar Charger' that you are attempting to replicate is fairly easily accomplished. The 'secret' is not the '108 Transistor' that all y'all are seeking; but rather, the pulsing characteristics.

By optimizing pulse width, and frequency, it is possible to 'tune' the device for the 'output' which is most effective. The pulse characteristics are by far the most important consideration. How those characteristics are attained is relatively unimportant provided the switching transistors are sufficiently fast and efficient. Circuit enhancements which assure fast and efficient switching are well established.

A certain experimenter in South Africa who was performing trials with the Bob Boyce Hex Controller was able to accomplish excellent results. His curiosity led him to 'improvise' certain operational features until he achieved a success that far exceeded his expectations.

The 'results' that you are seeking seem quite elusive because virtually none of the experimenters appreciate the criticality of the pulse characteristics.

Reliance upon an 'original recipe' to create a working replication is fraught with uncertainty. Too often, the important details are not provided. Such as pulse width and frequency and essential wave forms.

A belief that only one 'kind' of transistor is absolutely essential to 'make it work' belies lack of understanding.

It is possible to 'replicate' with what is common and inexpensive in most cases.

[Matthew Jones]

Even within a given 'type' of transistor there are large variations in the Current Gain from unit to unit. These variations in 'Beta' make part-for-part replication still a stab in the dark in many cases.

When one is aware of the principles involved in any particular 'replication' then one is able to make adjustments in the circuit parameters in order to compensate for device (transistor) deficiencies. Often times, using a Darlington pair in place of a single transistor is enough to provide the 'boost' that a deficient transistor - still within mfr. specs.- needs in order to make the 'replication' work.

Yes, it is possible to use 'silicon' in place of 'germanium' in virtually every application. In every case, the 'silicon' replication will work substantially better than the 'germanium' version.

One shortfall of the mechanical 'Tesla Switch' is 'contact arcing' when switching under normal load. By delaying load current 'pulsing' until all mechanical switches are in place and making contact, this problem can be obviated. With properly sequenced electro-mechanical relays and a 'synchronized' load current pulse, the complexity and losses of the 'transistorized' Tesla Switch can be overcome while easily eliminating the arcing at the contacts. This is a very easily accomplished enhancement of the basic 'Tesla Switch' which can be done with Silicon.

There are cases where the electro-mechanical relay may yet be the simpler and more effective solution. With a little 'creative help' from a Silicon semiconductor.

It is rather easy to get 'stuck in a rut' when one attempts to 'replicate' without fully understanding what is being 'replicated.'

Hammer down brother!!! Put some pictures up. Test results. Scematics. Somthing!
LOL gotta love the new guy.

Boy all the nasty thing I could write right now. But I'll refrain for a change.

Matt

[Matthew Jones]

A belief that only one 'kind' of transistor is absolutely essential to 'make it work' belies lack of understanding.

It is possible to 'replicate' with what is common and inexpensive in most cases.

No body said it was essential. What we said was we wanted to try them. No other kind has worked. Not even for the people who could possibly build one. So It was shot in the dark.
Now if you know somthing share it. PLEASE!!!.
If you talking out your ass well then go away, we gotta enough folks like that.

Matt