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Recent content by Thomasdj

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    Qeustion about servo drive/motor match

    Hi, I want to run a cnc spindle with a servo motor and yesterday I picked up a BNIB mitsubishi 750watt servo drive from ebay.. Can I use a 400watt servo motor if I adjust the "high torque limit" Pot/resistor to a fixed resistor with correct value? It's not because I don't like the 750watt...
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    CNC router Stepper driver design - help!

    what should be the spec router stepper Hello, I am new to steppers so need a little help designing a stepper driver/controller to my CNC router project. I need to drive/control 4 motors with the following specs: 2 x Astrosyn L189/4 Phase: Phase Current 1.6A Phase Res 2.65ohm Phase Ind 4.75mH...
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    Problem with the high hum in a tube amplifier for a guitar

    Re: Tube amp hum problem Hi Ram, Haha..No not Death..but you're right..it's metal-style with a lot of heavy bounce rythms, special/weird bridges a.s.o...(can hardly wait to get the amp in the rehearsal!) I actually can't remember..the effects are in the rehearsal room by now, and I'll bring...
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    Problem with the high hum in a tube amplifier for a guitar

    Re: Tube amp hum problem Ok Frank, Tomorrow I will take all my pedals home and see how the input/output is wired. At same time I will try to improve another issue. the effect chain is humming because of ground loops via the supplies (wallwarts and daisy chain). I'm thinking of a new setup for...
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    Problem with the high hum in a tube amplifier for a guitar

    Re: Tube amp hum problem Hi Frank! Guess you wrote while I was answering Ram:D I'll try that! It all makes sense Frank. However, this depends on how well maked my effect chain is!(see pic at bottom page 5 in this thread).. I think I will install yet another coupling cap directly at the V1...
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    Problem with the high hum in a tube amplifier for a guitar

    Re: Tube amp hum problem Hi Ram:D The input is the "guitar In" and outputs are for two amps. I don't know if it's a break-before-make switch but I do think so. I'll try to solder a resistor to ground, but if this does the trick, I really wonder why the "maker" of this circuit haven't thought...
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    Problem with the high hum in a tube amplifier for a guitar

    Re: Tube amp hum problem Hi Frank, The amp is now stable and works as it should! However, I cannot figure out how to make the switcher circuit. The attached pdf is the A/B-switcher I use now, - can you see anything that should indicate why the circuit pops when switching? is there something I...
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    Problem with the high hum in a tube amplifier for a guitar

    Re: Tube amp hum problem Hi Frank, I installed the J174 today and this actually improved the switching issue. The noise is almost gone, - I only get a little tik-sound when switching. The real improvement is that the tik-sound don't get louder when turning up the amp! It stays at the same low...
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    Problem with the high hum in a tube amplifier for a guitar

    Re: Tube amp hum problem Hi Frank, I see! ..the impedance could be too high. I plan to use these LDRs with very low light-resistance (a few ohm) and very high dark-resistance (<50 Mohm): https://www.datasheetcatalog.org/datasheet/perkinelmer/VT500.pdf (on page 43) I tried to make the preamp...
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    Problem with the high hum in a tube amplifier for a guitar

    grounding point in tube amp Hi Frank, I'm thinking of building an amp switcher into the footswitch chassis (I use two amps, - one for high gain distortion and digital effects and one for warm clean sound with analog effects). Currently I use a passive A/B-switcher but it is not "dead" sead...
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    Problem with the high hum in a tube amplifier for a guitar

    tube amp hum with cable only I'll try the split supply :) Frank, I think the mix pot is to mix the original signal (dry) with the effect return signal (wet)..if cutting the original path, wouldn't I get the wet added signal only? Thanks Thomas
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    Problem with the high hum in a tube amplifier for a guitar

    tube amp connecting heaters ac dc Here is the link to the panel meter: https://www.circuitspecialists.com/images/CX101A&B&BG.pdf I only need the 0 - 200mV DC range so I wouldn't need any additional resistors, right? would that mean that I will have to connect pin 2,5 and 6 together as ground...
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    Problem with the high hum in a tube amplifier for a guitar

    vacuum tube hum when cold Another question Frank, Would this FX-loop mod work? to switch between serial and parallel effect loop..
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    Problem with the high hum in a tube amplifier for a guitar

    increasing hum in my tube amp Hi Frank, Yes, I'll order the JFETs and see if this minimize the problem.. Thank you for your help! Thomas
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    Problem with the high hum in a tube amplifier for a guitar

    ground star tube amplifier Hi Frank, I will set all tubes to 70% of plate dissipation. Another thing will also "move" the bias current, - the rectifier select, since the plate voltage will be lower when using rectifier tubes. I use the GZ34 instead of 5U4G, since the voltage drop is only...

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