![]() It might be possible to configure the circuit to run off of your 16V DC laptop adapter but you would need to make a Virtual ground circuit. you will get very little to no output if you are using a single DC supply as the input needs to be referenced half way between the + and - voltage so that the output voltage can swing positive and negative. batteries planned for later) with a 16vDC 7.5 amp laptop power supply.Īt single 16vdc supply is not sufficient to power this chip, at least with this schematic, if you had two 16v supplies you could make a 2x16v DC supply. Is the most likely issue the power supply? Would the 2 9v power source you describe be the first thing you would try? I have been powering it (during development. I don't find any shorts or cold solder joints. I have traced and validated some much of the circuit. No sound until the signal gets higher than it should be, and then only pops and clicks. I also tried disconnecting the OPA137 (though not replacing it yet with a cap). When I feed a bit stronger signal in, I get a bit of quiet popping, but no intact sound.įirst, I built it with the OPA137 section in, as I didn't yet understand how to remove that safely. I'm thinking that at Mic input levels, the sound out should be clearly audible via headphones. At first I thought I was getting no sound out. UPDATE: So, I built it and double checked, but apparently have an error. Mouser has a nice Bourns 2K reverse log pot, so that at least is covered. After going through it again, I found them labeled in a different diagram in the spec sheet. Unfortunately I wasn't able to understand the pinout diagram, as I didn't know what RG1 and RG2 meant. If I am omitting that whole powered mic section, do I need to modify the section around R4 and R5 to mimic the way the circuit would look if the powered mic section were installed but turned off? ![]() And, there is a >50K path to ground through R1, 2, and 3. So, the little gain control (via 2k pot) must go between pins 1 and 8, labeled RG1 and RG2 elsewhere in the spec?ģ) I notice that in the schematic, when the +48v mic power is switched off, there is still a 13.6K additional path between the Vin + and - through R1 and R2. I assumed that the minus sign means pin 2 (labeled Vin- elsewhere in the spec) and the + sign means pin 3 (Vin+). So, do all the ground points and the -15v (pin 4) and the diodes going to -15v all just go to a ground bus connected to the negative terminal of the battery?Ģ) Pins 1, 2, 3, and 8 are not identified on the schematic. There is no ground that actually goes to ground. 1u I unserstand that this circuit will work with a passive mic if the active mic section is switched off (or properly remived) The hope is to make it work with a lapel-type mic, but I can switch to a different passive type mic if needed.ġ) This is battery operated in a plastic case. By "a large capacitor" do you mean something like a 100u electrolytic, with positive to pin 6, and negative to ground, removing the other 3 parts (OPA137, 1M res and. I didn't realize anyone I might be able to learn from another example, PCB or not, but I am just building this on I wondered what "Optional DC output control loop" meant. I have to say I have been waiting for this to come out and the initial reviews are excellent – I can’t wait to get hold of the link to try it out.Thanks for the help, and sorry for the late reply back. You can buy more amps and pedals individually, or you can get AmpKit+, which gives you another 3 amps, 4 cabinets and 8 effects pedals for £11.99 – saving money on buying them individually. The software also includes a tuner and metronome – Agile being renowned for their existing tuner app. With the free bundle you get one Amp (but with both clean and high gain channels), 2 cabinets, 2 pedals and two microphones. The initial software is free, but you will need a way of plugging your guitar into your iPhone – and Peavey helpfully sell a widget to do that for £30. Not only does it replicate a guitar amplifier, but different cabinets, effects pedals, microphones and you can even alter the microphone placement. Musical giant Peavey have linked up with AgilePartners to produce AmpKit – an app that turns your iPhone or iPod Touch into a perfect guitar amp simulator.
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