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Topics - m-Kresol

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Build Reports / Yorkshire Echo
« on: April 26, 2017, 12:57:16 PM »
this is the Yorkshire Echo by "juansoloFX", which was part of the pcb bundle I got for the BOTY contest. Thanks to John and Cleggy for their noble donation.

The build itself went together really smooth and it sounds great. I'm very happy with how it turned out, one of my best builds so far, if I might say so myself. The sparkling of the metallic paints goes very well with the space theme. The bezel will get replaced with a round one, as soon as they come in. I used this build to write up my etching tutorial in all detail, if anyone is wondering how I do it. LINK


Open Discussion / New Offset guitar and DIY guitar stand
« on: April 22, 2017, 08:39:25 AM »
Hi fellas,

I bought a new guitar a few weeks back and it's my first offset guitar. I was aiming for a Jazzmaster when I found this one locally for a very good price and it pretty much is everything I could have wished for (eg. no tremolo, satin finish neck, not the ugly Fender strat headstock). It only has two minor scratches on the back but otherwise is like new.

It's a Hohner Reno and I have almost no info about other than it was build from 1998 - 2002. Timbo is winding some new pickups for me, which will make this one near to perfect.

When I was home for easter I used my dad's workshop to build myself a multiple guitar stand. Thanks to Brejna for posting his build a while ago. I was hoping to get some dark wood, like walnut, but I couldn't justify paying more for a piece of lumber than what I paid for most of my guitars, so I went with cheap spruce from the hardwarestore instead and gave it an oil finish.

Open Discussion / hohner guitars - any good
« on: March 26, 2017, 05:11:49 AM »
There's a jazzmaster/tele mashup Hohner guitar for sale locally - for very little money I have to add - and I was wondering if any of you have experience with their electric guitars. This one is a "Reno" modell, which is not produced any longer apparently, they only have acoustic and headless nowaydays.

I was planing on getting a jazzmaster, but this one is very nice optically and I didn't want a trem anyways. Do you think exchanging the pickups for regular jazzmaster PUs would be hard, ie. especially the cavity for the neck PU?

any advice is appreciated, thanks.

Tech Help - Projects Page / PSU HiFi Amp
« on: November 23, 2016, 10:55:51 AM »
You can ignore my request. It's not working yet, but I got a professional to look at the schematic and he confirmed it's good as is. Wasn't sure if he would reply to my email, so I posted it here too. thanks anyways.

I'm not quite sure where to put this, as it's neither Etcher's paradise nor a madbean project, but one of my own.

So, I was hoping to get a second set of eyes on my schematic for the PSU for my HiFi amp. I tested it yesterday and I the rectifiers work. The heater side is ok. But the high voltage side, which is supposed to give 285V DC only gave 40V at first, the second try only gave 10V, and now I'm down to below 1V. The transformer works correctly, I have 250V AC at the input to the PSU and 360V DC at R1, but after R1 the voltage breaks down. Also the primary fuse blew one time, which is weird because I thought the secondary fuse would go first as no heater current is flowing anywhere (wires disconnected/floating). I should mention that I measured every component before soldering and suppliers are trustworthy.

I checked all components, reflowed everything and desoldered C5 and C6 as I suspected those (I had to desolder C5 before which is a pita because of it's size and feared that I overheated it). with only C5 or only C6 the result is the same. Only very little DC voltage after R1. I also checked the datasheets for pinout of the transistors.

I'm suspecting something might be wrong with my schematic to begin with. I'm not entirely sure about the voltage stabilisation parts. The Zener diodes bring the voltage down to 285V and open the MOSFET, which should give also a little below 285V at the output, which is stabilized by C8.

I'm appealing to the electronics gurus (Brian, Jon,...) to have a look, I'd appreciate it. Thanks

Build Reports / Liquid Mercury Phaser
« on: November 21, 2016, 07:15:25 AM »
drolo's fantastic Liquid Mercury phaser. Came together nicely without problems and the combination of yellow 5mm LED and 2 tayda LDRs works well and sounds nice. thanks to chuckbuick for the tipp.

I added a Tap sync jack which is basically just synchornising the 5V tap of the tap switch with other taplfo devices (in my case Jon's Cardinal tremolo). I might resolder it to the other lug of the jack. This way, if someone accidentally inserts the 9V supply there, it will only put GND on the 5V pad instead of 9V, which might damage the IC. I need to add the jack to the tremolo to confirm it works, but according to the datasheet it should work.

The etch turned out really well and the epoxy really brings it to live. Lots of detail on this one. First attempt at a multi-coloured theme as well. Lots of work putting tiny pieces of masking tape on there. I didn't have 6 knobs of the same kind, so it's missing one and the waveform selector will also get a white one in the future.

Build Reports / The Evil Twins (dminner coop dual reverb)
« on: October 11, 2016, 04:06:51 PM »
This is The Evil Twin, or better Twins. They were built in a labour trade with dminner over a long, long period. I think we started planing sometime in February or March. Dan did the artwork, etching and painting, I did all the electronics. It's a dual reverb with a send-return loop in between the effects and an order switcher. This means that in/out 1 can go to either effect and in/out 2 will go to the other. If nothing is inserted into the loop, they are directly in series via the switched jacks.

The dark side is a DBA reverberation machine workalike with the addition of variable decay (btdr-3h brick) and some power filtering/polarity protection. Following my labelling scheme, I call it the "Rubidium Reverb." The light side is a spring reverb using the small blue 2 spring tank by accutronics. The design is based of the reverb section of a Fender Blues junior and I had to run through 5 designs. Mostly it was about the power section, as 9V didn't give enough clean headroom for the opamp. Had to go with a charge pump in the end. Also, because of the lowered input voltage compared to a tube amp, I had to modify the gain makeup stage and added a boost to the end to get it to unity and beyond. I achieved both with a LBP1 booster. This one's called "Ruthenium Reverb."

the dark side gets quite weird on some settings (just like the original), very spacy and ambienty but can also do clean, regular reverb. very versatile. The light side has very much treble, which I couldn't alter in the end. We think that might be coherent to the spring tank due to the small size. Nevertheless, it sounds quite nice up to half of the blend knob, then it gets a bit icy for my taste.

both projects are shared on OSHpark and the build docs are linked there. I hope some of you will build either one. I also shared the order switcher with the send/return option. No idea if that could have been done with a 3pdt too, but i couldn't figure it out.

Here's mine all finished up. I obviously got the Evil Twin with a worn in finish. Both projects are designed for all board mounted pots and switches, but I had to wire some of them in. Still pretty pleased with the wiring considering what's going on in there. The spring tank is mounted to the lid of the enclosure and sits right between/above the stomp switches. Yes, you can make it warble and make noise by hitting the enclosure. To be honest, even hitting the bypass switch will give some warble, which is hardly noticable if you engage while playing though.

Dan got the Good Twin with a nice, unbruised finish.

spring tank attaches comfortably to the pcb via these connectors.

Still missing some knobs...

Group shot:

Dan should receive his shortly. I hope he'll do a demo ;)

Lastly, I've got one Ruthenium Reverb board (spring reverb) left, which is up for grabs. 10€ including shipping worldwide. First one to speak up in this thread gets it. paypal gifted please.

Build Reports / Dubnium Drive & Indium Indicator
« on: October 03, 2016, 01:03:19 PM »
My latest creations, the Dubnium Drive (DBA Interstellar Overdriver) and Indium Indicator (VU meter designed around the LA2284 chip). Thanks to Cody for tech help with the transistor selection, which led to me discovering a layout mistake (flipped transistors). The indium indicator is using 0805 SMD components, except for the trimpot, IC and the SS12 diode which is a bit bigger than 0805.

The layouts are shared in my oshpark account (through hole and smd version for the Drive) and build docs are linked there.

The graphics are courtesy of Peter Repovski, who was nice enough to allow me to use the comic and sent me a high-res verision. Etched, painted, sanded and clear coated. Turned out perfect, but shows again I can't drill straight. ;)

The video is just to show the VU meter. The sound recording is crap with my phone.

Build Reports / Dig Dug 2
« on: August 26, 2016, 04:16:44 AM »
So, I finally finished this one. Had to redo the etching three times, because I wasn't content with the results. The third time the depth was very low, but I just couldn't be arsed doing it again. It was supposed to be a two-coloured design with the squares on the bottom part filled in with black, but I've lost most of it while sanding. Also, I've used primer for the first time, which seems to make the paint way more durable.
In the end, I went with a used look. because of the low depth I sanded into the lowered areas too, so I just went ahead and sanded the whole thing and worked the corners and such. I like how it turned out, even if it wasn't my initial intention.

I had to take the whole thing apart. I had the sequencer going, but the pattern indicator didn't light up and no effected signal was coming through. As suspected, the sequence was going to GND after the step LEDs. Turns out you can't even buy LEDs @ tayda anymore. ALL the leds had bare leads instead of being covered by the plastic lens/housing. A few layers of nail polish did the trick though.

Very fun circuit, I still have to play with the internal trimmers. Thanks Brian



Open Discussion / DIY oscilloscope
« on: July 18, 2016, 11:01:51 AM »
does anyone have experience with simple scopes like this?

would be cheap and could just work well enough for setting up analogue delays and checkinhg easy things...

Build Reports / Total Recall - Vintage Memory Man
« on: June 08, 2016, 09:22:23 AM »
I'll just leave that hear. Reverse etched "Delayrian" (badumm tiss!), 4x MN3008 from Paul @ I've got quite some time ago. Still need to fine-tune the biasing, but it's pretty good as is.


Build Reports / Strontium Screamer - TS808
« on: May 28, 2016, 08:50:51 AM »
A friend of mine wanted to do SMD, so I designed a TS808 pcb in SMD for 1590A. It turned out pretty good, the only thing I miscalculated was how little space there is in 1590A's. Now I remember why I've only built one so far ;). I designed the pcb for board mounted pots, but should have turned the top row around so they are under the pcb to gain some space. worked out in the end, but it was a very tight squeeze with the Lumen; a 3PDT would probably be easier to do (the last picture was taken during wiring to show how close it actually is).

Anyways, the design is a stock TS808 basically copied from Brian's 'Green Bean' project. I've added extra diode pads, so one could use symmetric, asymmetric Si or Ge diodes if preferred. I went with the stock 1n914 symmetrical option. The updated pcb is shared on oshpark with a linked build doc if anyone is interested; also I corrected a mistake of v1.0 which had a wrong transistor pinout, so I had to flip them for my build.

Reverse etch with metallic green. Lower part has a blue flip-flop on top with a gradient towards the lower end. It's hard to capture on photos, but it actually changes colours depending on the angle you look at it. The graphics are partially taken from the schematic. don't try to build it going from the exterior graphics though :p


General Questions / LT1054 vs. 7660SCPA/1044SCPA
« on: May 01, 2016, 11:41:48 AM »
Hi everyone,

I'm prototyping for a cooperation with Dminner atm, but I'm having problems with my charge pump setup. Ideally, I want to create +15V-15V from a 9V input. I wanted to do so using a LT1054 Charge pump and the circuit depicted on page 18 of the data sheet ( I drew up a layout, etched it and totally screwed up getting only +6V and -0.3V...
So, I had another go at it today with a very layout that checks out as far as I can tell from the layout. the problem with the etched one was too little spacing and a very tight layout. Anyways, I managed to brake off a leg of my last LT1054 charge pump and wanted to know if its interchangeable with a 7660SCPA ( or 1044SCPA charge pump that I have on hand. The pinout is the same, yet neither of them has the schematic for the voltage doubler/inverter in the data sheet. It only has the one for voltage inversion and positive doubling, so getting +18/-9V.

thanks for looking

Open Discussion / Well, that's gonna be an awesome weekend
« on: April 15, 2016, 11:55:49 AM »
Went out of work today to find this in our University's yard: a freakin' robot band! How awesome is that?!? there's gonna be a "maker's fare" of some sort.

Also, I just handed in my PhD thesis. After 2.5 month of constant work, 6 days/week, 60-70 hours/week including stress-induced Tinnitus (hooray!), I'm finally done! you can't imagine the feeling when you slowly rename a pdf "Dissertation-Felix...pdf" Glorious! Enjoy your weekend!

Build Reports / Tap Tempo Cardinal
« on: March 28, 2016, 09:32:22 AM »
I finally finished Jon's Tap Tempo Cardinal Tremolo yesterday. I really like the sound!
I had a broken electric cap killing the supply voltage. Of course, I had already boxed it, because it had quite a bit of offboard wiring involved. Taking it out wasn't as bad as I anticipated, but at least I figured out the problem fast enough.

Enclosure is etched with NaOH. Because of the fine lines, I didn't sand the surface, but rather scratched the paint off the raised parts with a syringe needle and a spatula under a magnifying lamp, which took me about 1 hour and explaining what I'm doing late night in the x-ray lab to a professor :)



Tech Help - Projects Page / Total Recall, compander
« on: March 26, 2016, 02:07:48 PM »
hey guys,
Finished my total recall today but I'm not getting any love from it. started the biasing procedure but not a sound from the first MN3008 (got them from Paul @diygp). Started taking voltages and I traced the problem to the NE570 compander (got that one from banzai). all voltages check out except for pin 5, 6 and 7. Here are the values, wrong values bold, should-be values in brackets.

NE 570 (all values negative)
13.8   13.8
13.0   13.0
13.0   13.0
14.8   0
7.5 (13.0)    13.0
7.5 (13.0)    8.6
13.5 (4.7)    6.7
13.0   13.0

Supply is the recommended EHX PSU, I'm getting -15.07 V from the 7905 regulator, so that checks out. As a consequence of the increased output voltages from the ne570 (pin 7), also IC3 A pins 2 and 3 are increased. Readings for CD4047BE are also a bit off, but not near as drastic as the NE570.

CD4047BE (all values negative)
7.46 (7.94)    0
7.63 (7.09)    7.4 (7.0)
7.57 (6.91)    15.0
0          7.5
0          7.5
0          15
15.07   15

I've checked the components around the NE570 (R9-R12 & C6-C10), all have the correct value, I also reflowed the area. I measured the components too, everything checks out, but I cant get a reading from C7. Could that mean, it's a bad cap and could that cause the issue? I didn't want to desolder right away as I hate doing that...

I also traced the signal, it reaches Pin 6 of the NE530. Nothing after it.

Here are some pics:

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