I'll second Mark's suggestion. A Mega328 or equal is possibly the best DIY investment you can make besides a good DMM. Also available on Amazon in many versions for very few $.
I always got LED's installed backwards until I finally got it through my thick skull that, unlike a diode rectifier circuit, the negative lead of the LED is connected to the positive voltage source.
I always got LED's installed backwards until I finally got it through my thick skull that, unlike a diode rectifier circuit, the negative lead of the LED is connected to the positive voltage source.
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Take a look at this post:
https://www.diyaudio.com/forums/pas...s-diy-headphone-amp-guide-99.html#post5660813
Basically you can try it without the cap, as some have experimented without it, just bear in mind that it all depends on what is driving it on the input. With the cap there, it generally will color the sound, so experiment and make it work for your particular setup; that is the fun of DIY!
I could not find equivalent transformer on Mouse, and ordered from digikey.
As for C1 and C5, i replaced then by a wire, as my source for less than 0.3mV of DC.
In addition, I think that the topology inherently gets rid of DC before output, as I tried to add dc with a generator while testing on scope and dummy load.
As for C1 and C5, i replaced then by a wire, as my source for less than 0.3mV of DC.
In addition, I think that the topology inherently gets rid of DC before output, as I tried to add dc with a generator while testing on scope and dummy load.
Have now completed and run a quick sound test. Initial impressions are v positive eventhough I have a pretty standard OP amp (The SMD one I ordered didn't fit onto the adaptor pad to transform it into a DIP 8 so I need to re-order another adaptor). I think I need to make some adjustments to the gain or potetiometer though. When I use my MC phono stage as an input I'm getting volume through eventhough the potentiometer is on 0 (Alps 50K). When I use the output from my record deck directly as a source (no phono stage) the volume is too low. I'm driving some Shure 1840s which are 65 ohm impedance. Any recommendations as to what needs to be adjusted?
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A bit unusual but now housed in an up cycled vintage style radio. With the wooden enclosure I have a question about grounding. If I create a star point with the earth in the iec then where does this connect to the pcb? I assume the signal ground can also be tagged here via the suggested capacitor?
Still having issues with the levels. I have a fair amount of hum when there's no signal and some volume when the pot is on full resistance and I'm using my MC phono amp as a source. I have a 100k alps fitted and currently have an OPA 1612AID Op amp. Any thoughts? Change the pot or are there some adjustments to the gain I need to make?
How is your board grounded? Are your input and output grounds connected together and then to the mains earth via a 0.47uf / 250v capacitor in series? If not give that a try and it should eliminate your noise issues.
How is your board grounded? Are your input and output grounds connected together and then to the mains earth via a 0.47uf / 250v capacitor in series? If not give that a try and it should eliminate your noise issues.
I'm waiting for a cap to be able to ground the signal ground to the mains IEC earth. Hopefully this will resolve the hum. Am I right in thinking that the board itself is not grounded to th emains earth at any point but 'floating'? There doesn't seem to be any info anywhere on the build notes about this. I may also try some shielded cable as I'm currently using single strands for the signal input. Any thoughts on the levels? They seem pretty high as I have volume when the pot (100k) is on full resistance. If I take the source directly from the turntable the levels are too low. Are there tweaks to the gain that I need to make or do I need to alter the potentiometer?
I'm waiting for a cap to be able to ground the signal ground to the mains IEC earth. Hopefully this will resolve the hum. Am I right in thinking that the board itself is not grounded to th emains earth at any point but 'floating'? There doesn't seem to be any info anywhere on the build notes about this. I may also try some shielded cable as I'm currently using single strands for the signal input. Any thoughts on the levels? They seem pretty high as I have volume when the pot (100k) is on full resistance. If I take the source directly from the turntable the levels are too low. Are there tweaks to the gain that I need to make or do I need to alter the potentiometer?
The chassis is directly connected to the mains earth, then Signal 0V is connected to the chassis through a capacitor from the RCA ground pins.
This is the only location where Signal 0V connects to the Chassis Earth as far as I can see.
That's what I thought. I have a wooden chassis so will be connecting signal ground to mains earth via the capacitor and a star point. The pcb itself is therefore not grounded to the chassis so left floating as far as I understand it?
This is the only location where Signal 0V connects to the Chassis Earth as far as I can see.
That's what I thought. I have a wooden chassis so will be connecting signal ground to mains earth via the capacitor and a star point. The pcb itself is therefore not grounded to the chassis so left floating as far as I understand it?
Since the photo I have connected the signal ground to the pad next to the pot and added 2 x 2.2uF Mundorf caps after the pot. As you can see the transformer is a slightly smaller one than the one suggested (15-15v) I'm using an Alps 100K and my source is a phono Amp and as a source an MC cart on a Turntable...
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