Hey-Hey!!!,
The current regulator is indeed a useful circuit. I prefer the MOSFET type since they can also do service as a mu-follower.
A few common points though...have you folks considered using SMT devices? As gate/grid stoppers, they are quite nice, in that there are no leads to move the resistive element further away, but that could also be considered their downfall...
cheers.
Douglas
The current regulator is indeed a useful circuit. I prefer the MOSFET type since they can also do service as a mu-follower.
A few common points though...have you folks considered using SMT devices? As gate/grid stoppers, they are quite nice, in that there are no leads to move the resistive element further away, but that could also be considered their downfall...
cheers.
Douglas
Brace yourself for -probably- the most stupid q:
Why are there 3 connections? For source you'd need a B+ and anode connection. And there's no Mu follower...
What is the difference in npn and pnp axcept for different layout and parts? One for sink,other for source?
I'm just frustrated i can't figure that third connection out...
Why are there 3 connections? For source you'd need a B+ and anode connection. And there's no Mu follower...
What is the difference in npn and pnp axcept for different layout and parts? One for sink,other for source?
I'm just frustrated i can't figure that third connection out...
Yes, PNP for source, NPN for sink. We'll have some documentation soon on what each is really intended for.
As far as hookup, you need the third terminal to supply the reference string. The reference string is the resistor and two LEDs that determine the base (and hence emitter) voltages. You want those constant and known, so it's usually fed from some stable source of DC tapped elsewhere in the amp.
As far as hookup, you need the third terminal to supply the reference string. The reference string is the resistor and two LEDs that determine the base (and hence emitter) voltages. You want those constant and known, so it's usually fed from some stable source of DC tapped elsewhere in the amp.
Has anyone tried using the BSP139 yet ? It's an SMD depletion mosfet and you can build a pair of them (as anode loads) onto a scrap of copper clad board the size of a postage stamp , complete with trimpots ! Solder the BSP's drain pin and tab to the copper clad and lift the gate and source pins , add the gate stopper resistor and source pot and voila ! A high impedence CCS . No negative supplies are required and also a 'mu' output is available .
cheers
316a
cheers
316a
Hey-Hey!!!,
Just so long as you use two. What ever parts I have employed in the build of MOSFET current regulators is eclipsed by an order of magnitude by the choice to use two in cascode.
What is the D-S voltage tolerance of those SM devices? how about their D-S on resistance? How much wattage can they dissipate?
cheers,
Douglas
Just so long as you use two. What ever parts I have employed in the build of MOSFET current regulators is eclipsed by an order of magnitude by the choice to use two in cascode.
What is the D-S voltage tolerance of those SM devices? how about their D-S on resistance? How much wattage can they dissipate?
cheers,
Douglas
Hi Douglas,
Take a look at the Infineon website , specs are there , think it's about 60 ohms Ron from memory , 1.7w diss , can't remember the D-S limit . Yet to try cascoding , still messing around with the filament batteries at the moment , will get the other two soldered in once I've got the thing running properly
your mate in London
316a
Take a look at the Infineon website , specs are there , think it's about 60 ohms Ron from memory , 1.7w diss , can't remember the D-S limit . Yet to try cascoding , still messing around with the filament batteries at the moment , will get the other two soldered in once I've got the thing running properly
your mate in London
316a
Hey Gents,
Thanks for the general info, and exactly for the maker. I downloaded the data sheet. D-S is 600V. It's maximum battery free use is limited to about 5 mA. Any more than that and the R-set is going to be quite small.
Anyway, for voltage references, the 600V tolerance is nice. Even better than the LND150's 500V. These usually wind up drawing less than 2 mA so it is quite useful. Must get some.
And one more thing, any takers to split a few hundred DN2540? That one remains the dissipation king thanks to the TO-220 case and its heatsink-ability. Drop me a PM if you wish.
cheers,
Douglas
Thanks for the general info, and exactly for the maker. I downloaded the data sheet. D-S is 600V. It's maximum battery free use is limited to about 5 mA. Any more than that and the R-set is going to be quite small.
Anyway, for voltage references, the 600V tolerance is nice. Even better than the LND150's 500V. These usually wind up drawing less than 2 mA so it is quite useful. Must get some.
And one more thing, any takers to split a few hundred DN2540? That one remains the dissipation king thanks to the TO-220 case and its heatsink-ability. Drop me a PM if you wish.
cheers,
Douglas
Oh, and for the Infineon part, it was BSS126 and it only comes in 3k reels. fortunately they're only $0.18 each. Or maybe I'll find some different quantity.
Going to make a call to Mouser and see if I can get another 100 of the Supertex DN2540N5 in any case. Might just get 200, but consider how much cheaper it would be to use IRF820 instead...or another enhancement mode part and pay for some batteries.
cheers,
Douglas
Going to make a call to Mouser and see if I can get another 100 of the Supertex DN2540N5 in any case. Might just get 200, but consider how much cheaper it would be to use IRF820 instead...or another enhancement mode part and pay for some batteries.
cheers,
Douglas
Standoffs for mounting.
When I did the Baby Huey Amp the diffamp CCS were done on the small prototype PCBs you can buy at the usual suspects stores.
By applying a file to shift the holes 0.05mm I found I could use stadoffs on the back of tube socket mount bolts so I did'nt need extra holes drilled in the chassis.
Has any attention been paid to standardising the mounting holes to an octal or noval socket mount hole spacing? or are they too big for that?
Thanks guys for your efforts to make we DIY'ers life easier.
Cheers,
Ian
When I did the Baby Huey Amp the diffamp CCS were done on the small prototype PCBs you can buy at the usual suspects stores.
By applying a file to shift the holes 0.05mm I found I could use stadoffs on the back of tube socket mount bolts so I did'nt need extra holes drilled in the chassis.
Has any attention been paid to standardising the mounting holes to an octal or noval socket mount hole spacing? or are they too big for that?
Thanks guys for your efforts to make we DIY'ers life easier.
Cheers,
Ian
Quote:
I don't know how they work inventory, but when I ordered them, they quoted an 8 week leadtime. And that's what they took. So it looked like they were still replenishing stock.
I think if you don't have to wait 2 months its called JIT(just in time)
it allows them to run with their shelves bare and you the customer to wait for the parts. This way you appreciate them.
I don't know how they work inventory, but when I ordered them, they quoted an 8 week leadtime. And that's what they took. So it looked like they were still replenishing stock.
I think if you don't have to wait 2 months its called JIT(just in time)
it allows them to run with their shelves bare and you the customer to wait for the parts. This way you appreciate them.
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