Hi,
a dimensioned Bonsai ready for layouting in either TH or SMD style, with suggestions about devices, power supply range, etc. had been shown in #12, #29 and finally #79.
Unfortunately though, it seems no one really read thoroughly and wasted a thought
And now the Bonsai has become a Borbely, a simple two JFET Buffer
BTW: with matched JFETs and spending the upper JFETs the same source resistors as the lower JFETs, the output cap could be omitted with alltogether.
You´re really a funny bunch, guys
jauu
Calvin
a dimensioned Bonsai ready for layouting in either TH or SMD style, with suggestions about devices, power supply range, etc. had been shown in #12, #29 and finally #79.
Unfortunately though, it seems no one really read thoroughly and wasted a thought
And now the Bonsai has become a Borbely, a simple two JFET Buffer
BTW: with matched JFETs and spending the upper JFETs the same source resistors as the lower JFETs, the output cap could be omitted with alltogether.
You´re really a funny bunch, guys
jauu
Calvin
Guys, I already laid the board out. I will order this week 2 for testing.
I've written up an article as well, but can only publish after I test the board. ( gotta get it 100% right ya know!)
I will post up the layout and schema later tonight.
I designed it for an Alps RK27. The board measures 25mm x 48mm and sits on the Alps pot directly.
I've written up an article as well, but can only publish after I test the board. ( gotta get it 100% right ya know!)
I will post up the layout and schema later tonight.
I designed it for an Alps RK27. The board measures 25mm x 48mm and sits on the Alps pot directly.
Hi,
a dimensioned Bonsai ready for layouting in either TH or SMD style, with suggestions about devices, power supply range, etc. had been shown in #12, #29 and finally #79.
Unfortunately though, it seems no one really read thoroughly and wasted a thought
And now the Bonsai has become a Borbely, a simple two JFET Buffer
BTW: with matched JFETs and spending the upper JFETs the same source resistors as the lower JFETs, the output cap could be omitted with alltogether.
You´re really a funny bunch, guys
jauu
Calvin
Yes you are right Calvin, it is quite possible to get the offset very low. But the FETs need to be well matched - I think dual LSK489 would be good here but they are hard to get and without the cascode, you need low input capacitance. Other option is a trim pot, but I tried to avoid that.
This design does not need matched FETs because the lower FET sets the source current and is sized to fall below the worst case Idss
No originality claimed for the circuit (originally published in 1960s I believe) and indeed Borbely and Pass (B1buffer) are very good designs. Hopefully though, this one is very compact and uses a high quality pot. Sims indicate very low distortion, as reported by NP and EB.
Last edited:
No at all, Calvin.Unfortunately though, it seems no one really read thoroughly and wasted a thought
(nanos gigantum humeris insidentes)
Tschüß
Here's the link Bonsai: RK09L12D0A1T ALPS | Mouser
But the way you have designed it for the RK27 is even better!
I did complete the layout but never built it so was reluctant to publish the board in case there were errors.
I can later today attach the write-up.
I am moving now so digging the layout up will have to wait.
The smallest SMD size was 1206. These are very easy to put down but YOU MUST USE A FINE TIP SOLDERING IRON, 0.8 mm solder and a pair of fine tipped tweezers
I can later today attach the write-up.
I am moving now so digging the layout up will have to wait.
The smallest SMD size was 1206. These are very easy to put down but YOU MUST USE A FINE TIP SOLDERING IRON, 0.8 mm solder and a pair of fine tipped tweezers
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.