As far as i can see the photo diodes do not deliver enough current. The LC Audio MC stage runs on 1mA as far as i can see. For a bipolar this can be enough because Gm is 10 times higher at the same idle current a Fet consumes. I could imagine that we use a solar panel though. For example the ASI-F2/2 delivers 12V, 125mA and i can get it for 19,95€ each.
Jim Williams (RIP) addressed this in an application note: "775 nanoVolt Noise Measurement..."
http://cds.linear.com/docs/Application Note/an124f.pdf
I also think i holds some promise, but like with all new things and concepts.. you never know...
but for sure simulation did show some promise....
Fun to see a practical implementation. the boards are with an lot of R-C filterings which off course ca be left un-populated...like the input which is with 4 parallel Jfet sets, can be built with a single set..
the circuit currents can be adjusted with resistor values.
but for sure simulation did show some promise....Fun to see a practical implementation. the boards are with an lot of R-C filterings which off course ca be left un-populated...like the input which is with 4 parallel Jfet sets, can be built with a single set..
the circuit currents can be adjusted with resistor values.
Michael, i am sure i can make it work. I use RC filtering a lot too. I like passive or non feedback filter solutions. I have not fallen in love yet with shunt regulators though. On some of my designs they worked well, on others i ran into oszillation but when it comes to PSU i am a bit challenged.
I worked a bit more on the PEN pre-pre. I am now back to Euvl´s AC coupled design and i found out that the Fet´s have to be matched well to make the circuit work. i hope i find the time today to make something satisfying.
I also have not given up on the balanced transimpedance phono. I think i have an idea that works. The input stage is now reconfigured for very low DC into the cartridge and i have added an inverted INA to make use of both inputs. An even better solution would be to use a fully balanced OPamp like the OPA1632 as the second stage and also include the RIAA there.
I worked a bit more on the PEN pre-pre. I am now back to Euvl´s AC coupled design and i found out that the Fet´s have to be matched well to make the circuit work. i hope i find the time today to make something satisfying.
I also have not given up on the balanced transimpedance phono. I think i have an idea that works. The input stage is now reconfigured for very low DC into the cartridge and i have added an inverted INA to make use of both inputs. An even better solution would be to use a fully balanced OPamp like the OPA1632 as the second stage and also include the RIAA there.
Hi Joachim and you all
I have been folowing this quite a bit and having finished (well almost) my F5 and getting ready for a decent Preamplifier to go with it.
So Phono stage be the next to start learning about.
I have at present a balanced in passive RIAA MC phono stage
Is powered by Lead Acid rechargable bateries at 12 V rails and has been so for the last 3 years
I have considered using super capacitors and to match the LA 2.3 AH cells It would cost about £300 (for 2 15 V capacitors )wich IMO would not be a problem only reason I did not go for it was that they would not sell me Just the 2 capacitors I needed
So maybe if you could get them...
Only problem I have found with the bateries is that they do not charge/discarge at the same rate so I am using a buffer to keep the ground right in the midle maybe that would be ok for the caps as well
Any way Joachim I find this tread realy interesting and realy apreciate all your efforts
if I dont post here is just because I am out of my depth but I am learning a lot so tanks.
I have been folowing this quite a bit and having finished (well almost) my F5 and getting ready for a decent Preamplifier to go with it.
So Phono stage be the next to start learning about.
I have at present a balanced in passive RIAA MC phono stage
Is powered by Lead Acid rechargable bateries at 12 V rails and has been so for the last 3 years
I have considered using super capacitors and to match the LA 2.3 AH cells It would cost about £300 (for 2 15 V capacitors )wich IMO would not be a problem only reason I did not go for it was that they would not sell me Just the 2 capacitors I needed
So maybe if you could get them...
Only problem I have found with the bateries is that they do not charge/discarge at the same rate so I am using a buffer to keep the ground right in the midle maybe that would be ok for the caps as well
Any way Joachim I find this tread realy interesting and realy apreciate all your efforts
if I dont post here is just because I am out of my depth but I am learning a lot so tanks.
Yes
Suplier I contacted was YEG
16V Module
http://www.yegultracapacitors.co.uk/PDFs/20100120_DATASHEET_16V_Santis.pdf
They would not suply me with the 2 I needed if I remember minimum quantity was 100 units at about £150 each.
From what I read around even less noise than Lead Acid and charge in seconds
Simple LM317 with current limiter is what I am usind to charge the lead acid and would have worked well for those as well
(apart that you could charge Lead acid at 1/10 of their capacity while super capacitors can charge in miniutes)
Suplier I contacted was YEG
16V Module
http://www.yegultracapacitors.co.uk/PDFs/20100120_DATASHEET_16V_Santis.pdf
They would not suply me with the 2 I needed if I remember minimum quantity was 100 units at about £150 each.
From what I read around even less noise than Lead Acid and charge in seconds
Simple LM317 with current limiter is what I am usind to charge the lead acid and would have worked well for those as well
(apart that you could charge Lead acid at 1/10 of their capacity while super capacitors can charge in miniutes)
Looks like they will actualy send me the 2
Just called them....
Probably a slow market let them bend minimum order qty rules
so 58 farads and Pd 2100W/KG
as those weight 550 Kg the realy hard bit for me is doing the mats and see how many sides of a LP I can play before voltagge drop to much or just go for it (I ma more bolts and spanners man) Just charge them while I turn the LP overand clean it up so if no output for say a couple of seconds make Charger kik in
no big deal as life cycle is 500.000 charges (at half rated voltagge to full voltagge at 25 C)
Discharge is linear not like bateries that are depleted at about 11.5V (for LAC 12V) if I remember
Just called them....
Probably a slow market let them bend minimum order qty rules
so 58 farads and Pd 2100W/KG
as those weight 550 Kg the realy hard bit for me is doing the mats and see how many sides of a LP I can play before voltagge drop to much or just go for it (I ma more bolts and spanners man) Just charge them while I turn the LP overand clean it up so if no output for say a couple of seconds make Charger kik in
no big deal as life cycle is 500.000 charges (at half rated voltagge to full voltagge at 25 C)
Discharge is linear not like bateries that are depleted at about 11.5V (for LAC 12V) if I remember
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