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Suzyj

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About Suzyj

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    Perth
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  1. It’s very soluble in isopropyl alcohol, so cotton buds dipped in iso to mop the majority up straight after soldering. Once the board is assembled I do a thorough scrub in hot (like 80 degree) water with some safe wash detergent in it, then rinse with deionised water.
  2. Normally I clean my boards before I take photos, as showing my flux is a bit like going out in my PJs. This thread, however, is about flux.
  3. There’s nothing wrong with SMD! I quite like building surface mount boards. I like to do an unholy mix of surface mount and through-hole, with plenty of MELF resistors and diodes.
  4. Additional flux is needed when you’re reflowing solder. A typical SMD process is to tin a pad, then bring the component into contact with the pad and reflow. If you don’t use additional flux then this doesn’t work. The flux in the solder wire is (barely) enough for the initial wetting of the pad. There’s none left for the subsequent melting. I do piles of SMD, and use a lot of flux. It’s the secret sauce for perfect solder joins.
  5. We're in a no-clean, water-based, lead-free world, and that sucks. Decent rosin paste flux is getting harder to find every time I go looking, and with the secrecy around formulations who knows what's in that stuff. Here's a recipe for paste flux just like your grandma made when you were a kid. Nothing but the finest free-range organic ingredients, and made with love. Cook some up and gift it to that special engineer in your life, or just make a batch for your own use. Seriously, this doesn't just resemble paste flux. It's the actual thing. It's not activated, which mean
  6. A pleasure! I'm getting such great warm and fuzzies reading of people building these. I'm assembling a pair of more uber ones on the bench today with Class G (erroneously referred to as class H on my silkscreens) output stages, in a 100W and 200W flavour. In simulation they show great promise. I can't wait to test them.
  7. I’m not aware of any substitutes for the Exicon parts. I designed it originally around Hitachi lateral MOSFETs, but they haven’t been available for some years.
  8. There are two manufacturers that I know of: CA Logic, distributed by future electronics, and Linear systems, distributed by micross.com
  9. Okay then, I'll go along with this. Here's what I've done: 1. In simulation: Insert a 10mV 10KHz AC voltage source in series with the zener, and simulate the circuit. Measured AC on output is 450nV, giving me 87dB rejection of voltage noise at this point. Like I said, good CMRR. 2. In reality: Stick a 12V zener in series with a 1K resistor. put that across my lab supply and put 5mA through the zener. Measure the voltage noise density across the zener with my 3585B. I measure 79nV/√Hz, flat across the band. For reference my 3585B does 11nV/√Hz with it's input shorted. It's a re
  10. I look forward to seeing the results of your simulations and measurements of your proposed changes on a board.
  11. TE 63756-1 https://au.element14.com/amp-te-connectivity/63756-1/terminal-pcb-tab-1-4mm/dp/2841308
  12. Instruments (ie guitars) are generally very high impedance. Cable for guitars is usually designed to have low capacitance, as cable capacitance destroys the high end on guitars. Resistance wise it’s low, just like other cable.
  13. I suspect the whole diffamp thing is confusing you. Can you agree that the node at the junction of R4 and R5 is a virtual ground due to the symmetry of the differential amplifier? If you do that, then split the whole input diffamp down the middle and look at one side. Q1a source goes to virtual ground via a degeneration resistor. Q3's base is held at 12V wrt our virtual ground, due to the 12V zener. The node formed by the emitter of Q3 and the drain of Q1a is at 11.3V. Our load resistor (R6) hangs off Q3's collector. It's a straightforward, uncomplicated cas
  14. Yup, all the parts are available. See the parts list. Also, I'm not a sir.
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