Understanding electricity in the TPU.

[forest]

Varistors are fine, what sparks are describing is also fine.That's how we return back into parametric resonance oscillators 

[wattsup]

Holy cow. I just got a response from SemiSouth for those two JFETs. I quoted the response below.

Quote
Below please find the information you requested:
10 qty of SJDP120R085 = $28.47 each with a lead time of 3-5 weeks upon receipt of your purchase order
10 qty of SJEP120R063 = $51.84 each with a LT of 8-10 weeks ARO.
Payment options:
Credit Card â€" if you pay via credit card, below is the  information we will need to process your order
- Type of card
- Name on card
- Account #
- Expiration date
- Code on back
- Zip code of billing address
Please note that this email quote is good for 30 days.  Let me know if you have any questions.
Unquote

Why are these JFETs so expensive. Probably because they can do things that no other components group can do. I planed on ordering 10 of each but now I will have to go back and ask for just a few of them and hope I do not blow them. 50 bucks per 63 for a normally open JFET. Hmmmmmmmm.

[gyulasun]

Hi Wattsup,

Well, I had thought of them as expensive components.  (And if you order less than 10 qty, the price may go up even higher for a single unit.)

I think you can "make" a normally open FET from the cheaper normally ON  SJDP120R085 type by using a ground independent voltage source like a battery (either a dry or a rechargeable).  Because you can bias the gate-source with the battery voltage by connecting it across the gate-source via a series resistor, with the appropiate polarity.

I think this as good for mainly test purposes, it will behave as if it were a normally open type and you have to control its gate-source with an input voltage that takes the FET to the ON state, whenever your input pulse defeats the battery voltage bias.  Very little current is taken from the battery.  The simplest control would be via an audio or a pulse transformer but a capacitive coupling can also be considered. In fact a 1:1 to 1:2 or max 1:3 transformer would be useful, working in the frequency range you would wish to operate the JFET switch, this may involve a wideband transformer which again may be expensive, so the capacitive coupling is more attractive.
If you need to see such a schematics, I can draw it if you wish.

rgds, Gyula

[wattsup]

@gyulasun

I will call them today to see if I can work something out with them for less quantity. Also their delivery delay is long and tells me that for them, this is a very new JFET production.

I don't know anything about SS component product launches but I could maybe presume that prices are always higher on the outset and should go down as their production increases.

But the idea of having such a non-dioded on/off switch being able to go up into the mhz range is so tantalizing that I will most certainly order some of those, maybe not 10 of each. lol

[wattsup]

Today I spoke with SemiSouth and ordered two of each. Those prices are unfortunately their retail price for quantities under 100. Above 100 u nits and price drops 40% and above 1000 units price then drop over 50%. But still it is expensive.

They told me the 63 model is their best seller but would not indicate the type of devices using it. For sure these must be expensive circuits if only one component can cost so much. Must be because they work.