JHS - Morning Glory [traced]
- irmcdermott
- Breadboard Brother
- Jack Deville
- Resistor Ronker
Information
I guess that's one way to track a board.
- Jack Deville
- Resistor Ronker
Information
- Bill_Mountain
- Breadboard Brother
As someone who has mixed feelings on JHS and as a bass player I'm surprised how much I want to try this pedal.
When I thought about building my own MBB clone I was going to put a transistor boost on the end to fix the phase. Well...there goes another idea I thought I had...
I still want to try one of these.
When I thought about building my own MBB clone I was going to put a transistor boost on the end to fix the phase. Well...there goes another idea I thought I had...
I still want to try one of these.
- grrrunge
- Diode Debunker
Information
My guess is a 100nF multilayer ceramic to help the electrolythic cap filter out high frequency noise in the supply voltage. Or a decoupling cap for V+irmcdermott wrote:Not sure what the yellow part is at the top
A true believer in the magic of Sherwood Forest Pedal Pirates
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New base of operations: http://www.knucklehead.dk
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New base of operations: http://www.knucklehead.dk
- grrrunge
- Diode Debunker
Information
Apparently the LM833 is an opamp specifically for audio purposes http://www.ti.com/product/lm833 . I've used those for quite a few builds, and tend to prefer those and TL072's for buffer, amp and filter stages among all the different dual op-amps i've ome across so farirmcdermott wrote:I wish I had one to fully trace, but someone I know who has a double barrel (but lives states away from me) was kind enough to let me know that the opamp is a LM833N.
A true believer in the magic of Sherwood Forest Pedal Pirates
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New base of operations: http://www.knucklehead.dk
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New base of operations: http://www.knucklehead.dk
- irmcdermott
- Breadboard Brother
On the silkscreen it's labeled "F1" and the symbol there is for a thermistor, but it definitely looks like a MLCCgrrrunge wrote:My guess is a 100nF multilayer ceramic to help the electrolythic cap filter out high frequency noise in the supply voltage. Or a decoupling cap for V+irmcdermott wrote:Not sure what the yellow part is at the top
- mozwell
- Breadboard Brother
As it is in series with the DC input power, it is most likely a special type of PTC. These are used as "electronic fuses" and can be quite small, for "tripping" at low currents.
There is a reverse power supply protection diode D2, if the DC supply is reversed, the diode will effectively short out the DC supply, as soon as this happens, the PTC will go high resistance, limiting any "fault" current, so as to not damage D2 or anything else on the pedal. In normal operation, the PTC has a few ohms of resistance, so will provide some RC filtering into the cap C1.
I use the high current ones all the time on the outputs of SS amps of up to approx 150W, as speaker protection, or two in parallel for up to 300W amps.
Its an excellent idea to use small ones this way in pedals.
What is marked on the device.
There is a reverse power supply protection diode D2, if the DC supply is reversed, the diode will effectively short out the DC supply, as soon as this happens, the PTC will go high resistance, limiting any "fault" current, so as to not damage D2 or anything else on the pedal. In normal operation, the PTC has a few ohms of resistance, so will provide some RC filtering into the cap C1.
I use the high current ones all the time on the outputs of SS amps of up to approx 150W, as speaker protection, or two in parallel for up to 300W amps.
Its an excellent idea to use small ones this way in pedals.
What is marked on the device.
- Attachments
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- bourns mfr.pdf
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- irmcdermott
- Breadboard Brother
I don't have the unit any more. But this is the only pic I got of that part and it unfortunately is blurry. The markings I could make out, and very well could be wrong were:
LF 30
BH3E
It was extremely difficult to read, so I have no idea if that is correct.
LF 30
BH3E
It was extremely difficult to read, so I have no idea if that is correct.
- irmcdermott
- Breadboard Brother
Also, I'm an idiot in the way I worded the, "there is continuity on both legs"... what I meant to say was:
Both legs are connected to +9v, one side is connected by a track, the other side is connected to the V+ plane
Both legs are connected to +9v, one side is connected by a track, the other side is connected to the V+ plane
- irmcdermott
- Breadboard Brother
I agree. It's excessive.freq67 wrote:Is that much filtering necessary??
So what exactly did they improve? Adding an output buffer? Their website claims "4X more headroom, 2X the available gain, and a more useful tone control"
- irmcdermott
- Breadboard Brother
Build doc for anyone who wants it.
- Bill_Mountain
- Breadboard Brother
Anyone notice that it used to be called a "discrete" overdrive. I wonder how JHS justified that bit of marketing?
You just gave me something to etch this weekend. Thanksirmcdermott wrote:Build doc for anyone who wants it.
- irmcdermott
- Breadboard Brother
Thanks for the direction on the PTC. I wonder if there were markings on the other side that I missed. It's definitely the Littelfuse series, and from the LF30 marking, it's the 30R series. Here is the datasheet. I just don't know which of these it is.
http://www.mouser.com/ds/2/240/Littelfuse_30R-19977.pdf
http://www.mouser.com/ds/2/240/Littelfuse_30R-19977.pdf