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MoonWatcher
Bronze Member
USA
98 Posts |
 Posted - 08/04/2008 : 20:51:20
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The search for mosfets smaller than the IRF's is over.
Going by Laurie's advice:
" If you want to stick with MOSFETs, I'd say the 2N7000 is your best bet.
The IRF510 has:
- V-DSS = 100V
- I-D = 5.6A
- R-DS(on) = 0.54 Ohms
- Input capacitance (1MHz) = 180 pF
The 2N7000 is physically smaller and has:
- V-DSS = 60V
- I-D = 0.2A
- R-DS(on) = 1.5 Ohms (approx)
- Input capacitance (1MHz) = 20 pF
Both are MOSFET technology, but are variations on the MOS theme so will sound different because of that.
Additionally, my guess is that the IRF510 will sound warmer because of the higher input capacitance. To be a fair comparison, maybe put a 47pF or 100pF capacitor across the 2N7000s.
Anyway, let us know how it goes if you try them?"
...I ordered a bunch of 2N7000s, and they sound almost identical to the IRF's, especially when you bypass them with a cap.
No more silicons or 1N400Xs for me - the mosfets are fantastic. They have just the right blend of bite and compression that most other diodes lack.
Of course when all of this experimentation was nearly complete, I found out that the OCD uses 2N7000s. Ditto for the Zendrive.
If you haven't tried them, I suggest you give it a shot. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/04/2008 : 21:49:18
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G'day moonwatcher! It's great that you are able to feed this info back into the group... thank you!
What are the exact connections you use? Which legs of the MOSFET?
Thanks!
Laurie. |
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 08/05/2008 : 00:20:08
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G & D are tied together to form the equivalent of the cathode, so all three legs are used (S is anode, obviously).
It's so nice to have something that fits pretty well where a 1N4148 used to be.
The IRF's looked scary crammed on the typical pcb... |
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leonard d rock
Silver Member
Philippines
301 Posts |
Posted - 08/05/2008 : 01:51:26
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hi moonwatcher. can mosfets be used on a ds-1? if yes, do i need to replace both clipping diodes with mosfets? please elaborate on this. thanks
LDR |
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 08/05/2008 : 05:44:46
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Hey Leonard -
Mosfets can be used anywhere that clipping diodes are used.
While the standard config. is your typical parallel pair, you can even use them in series, or even a single one!
And just like other asymmetrical setups, you can use a mosfet on one side, and something else on the other.
Here's a good tech article on mosfets as clippers:
http://www.muzique.com/lab/zenmos.htm
It also includes info on using zeners as clippers - something that you don't see done much (yet).
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leonard d rock
Silver Member
Philippines
301 Posts |
Posted - 08/05/2008 : 06:15:43
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thanks moonwatcher! i'll try this on my ds-1 as i'm trying to find a distortion tone different from the hm-2.
LDR |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 08/05/2008 : 12:38:17
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Hi MoonWatcher
Which Boss or other pedals did you fit the 2N7000 clippers into?
And in which configuration?
Fortunately, some years ago, I found a a heap of these being sold off, at one of the disposal electronics places I visit.
I purchased them because they were good quality Motorola Branded FET's
not to mention that the price was the best part of the deal.
I have used a few now & then as Buffers, but I prefer to use the VN22222 enhancement mode FET for Class-A Audio pre-amp front ends.
A bit tricky to Bias correctly, but worth the effort.
I have a pre. that is built with the VN2222's in my modest studio.
I run them pretty hot (V) rail wise, & it's worth it.
They are so quiet, I can't even get a reading, off my HP N&D set.
It might be worth inverstingating & experementing with the VN2222 as clippers?
What do you think MoonWatcher?
Regards Dr. Bob
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 08/05/2008 : 14:26:56
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Hey Good Doctor -
I'm putting them in ALL of my Boss pedals - SD-1, BD-2, MT-2, DS-1...
The VN22222's sound like a very interesting component for playing with. |
Edited by - MoonWatcher on 09/10/2008 17:23:35 |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 09/10/2008 : 17:38:35
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quote:
Originally posted by MoonWatcher
Hey Good Doctor -
I'm putting them in ALL of my Boss pedals - SD-1, BD-2, MT-2, DS-1...
The VN22222's sound like a very interesting component for playing with.
Hi MoonWatcher
I guess you got a little excited or trigger happy.
That's only 4 sets or 2's in the
VN2222
Apologies for being critical, it's just someone might come back complaining they can't source the VN22222 or a data sheet, for one.
We could always re-badge a few, & sell them as (SSC's) Super Special Clippers.
Only available from MoonWatcher & the good old Doc...
Regards Dr. Bob |
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 09/10/2008 : 21:55:42
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| If you use the MOSFET in G+D-S mode, you should also have a diode like 1N4148 in series to stop the MOSFET's body diode from conducting. Otherwise, it is like having two anti-parallel diodes. |
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 09/10/2008 : 23:40:08
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This is what I mean in a diagram,
One would treat this circuit as one diode. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 09/10/2008 : 23:46:28
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| Thanks! Probably best to use a GE diode to minimise the alteration to the tone? (due to increase in total forward voltage drop from the addition of the diode) |
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 09/11/2008 : 00:12:17
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True, GE diodes will probably be a bit better.
I say a bit because the forward voltage of the diode connected MOSFET can be between 1.8 to 3 V. So the 0.3 V difference between Si and GE diodes will be mostly masked.
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 09/11/2008 : 05:40:42
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I've got some Schottky BAT41's that I plan to try in tandem with my 2N7000's.
They're very similar to 1N34A's, and you find them in this combination in pedals like the Zendrive.
The best part is that they're as small as 1N4148's, and super cheap to boot... |
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linuxius
Copper Member
Switzerland
13 Posts |
Posted - 12/18/2008 : 10:08:30
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I am planning to fit my ODB-3 with 2N7000 FET's. But I am not sure which configuration to use. I have read http://www.muzique.com/lab/zenmos.htm and I am thinking about the second drawing using two FET's in series/reverse. This would also eliminate the need for a diode as cctsim stated.
Has anyone tried both setups and what is the tonal difference. I am looking for an Overdrive sound. I find the ODB-3 is more of a distortion right now and want to mod it so it would give more of a tube sound. |
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 12/18/2008 : 10:49:53
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| Managed to find one 2N7000 and might use it on a ZVex Super Hard on clone |
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Topic |
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The perfect mosfet clippers have been found!
