This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, January 9, 2017

Hudson Electronics Broadcast

Alright, back to the normal layouts. Here's a really unique overdrive pedal from Hudson Electronics in the UK. It features an onboard charge pump to take 9 volts up to 24, so be sure to use appropriately rated capacitors (min 35v for electros). The transformer (the big yellow thing on the board) can be found on Mouser and other online vendors. Because of the transformer I suggest building this in a 125B for the extra height. Here's the schematic for reference. From the Hudson Electronics description:

The Broadcast is a transformer coupled, discrete Class-A germanium pre-amplifier based on the classic broadcast consoles of the 1960s. In the low-gain setting, the Broadcast can cover everything from sparkling clean boost through to transparent overdrive, all with a healthy dose of volume available to push your amp. The Broadcast features a specially selected Triad steel-core transformer and a NOS germanium transistor. Advancing the gain on the Broadcast starts to saturate the transformer and the pedal’s discrete circuitry, giving rise to a gentle and dynamic compression coupled with subtle thickening of the midrange. With the gain switch in the high setting and the trim control wound up, the Broadcast starts to deliver heavier distorted sounds with a warm and fuzzy edge to them. The Broadcast covers a wide range of driven and distorted tones whilst remaining dynamic, responding well to pick attack and the subtle nuances of every player.


51 comments:

  1. I cannot agree if this one is "normal" one. LoL

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  2. Lol, dude, I've ordered 3 transformers from ebay yesterday because I was totally sure it won't take you long to make this layout :D

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  3. hi, is the schematic available? thanks!!

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  4. So far in the 18 months of building pedals, it's been all PCBs. How difficult of a project would this be for a first time bread-boarder type thing?

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    1. Or do you sell a PCB version of this?

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    2. Breadboarding or building on perfboard? If breadboarding, have at it. Breadboarding is the type of thing you can easily fix any mistakes as well as experiment. If perfboard, I would try something a little simpler to cut your teeth on. I could make you PCB, though note that the layout has not yet been verified. Shoot me an email if you want a PCB (gehringcustomguitars (at) gmail.com)

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  5. Friend: I checked this circuit. Thank you for your work!

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  6. The layout shows a 470uf electrolytic across the output from the charge pump to ground - but in the schematic it is shown as 120uf - why is this, and what difference will it make?

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    1. In the schematic there's actually 2, 120uF caps in the schematic. These capacitors are for power filtering, so I put in a 470uF in the layout to be safe. You can try different values if you want.

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  7. This circuit I did not start until I joined all the components, which are neither easy to find nor cheap. The capacitors put a nichicon, the 470uf eventually got lost in the post office, and I ended up replacing it with a 330uf, and I think there is not much difference, the transformer Triad Magnetics, and the transistor was more complicated, the price that ask for the OC71 is excessive, I tested with the ones I had here, and I chose the TG-5S (HFE100) I think it's from Poland. Sound is not easy to understand at first audition, it may even be a little disappointed. What stands out soon is the absolute silence, no background noise is heard, it's really class A amplifier, the pedal is presented as a booster, but the gain is not very high, at least in my case I find it much more weak that most of the other boosters I've tested, but (there's always a "but" on this pedal) the bandwidth that comes out of this pedal is too big that it seems we heard the guitar breathing, the overdrive with the transistor I used was very smooth, but it was to realize that even though not knowing much of electronica, there is a division of the sound a clean part direct to the output, and another goes through the transistor just to give a scent. After you start playing, you become addicted to the sound, and you can not stop.
    The circuit is as always, five stars, my transformer had to bend its legs, because the space between them is another 4mm. I have not tested it yet with other effects, but I think it should sit very well at the beginning of the chain with the clean adjustments, leaving a trail of magic!

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  9. Where can I find a switch like Hudson uses? It has two connections and is pretty heavy duty looking. How do I use a switch with three connections, or can I even use that?

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    1. All the gut shots I've seen of Hudson pedals have a pretty standard 3PDT footswitch... You talking about a Carling switch?

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    2. Look at the inside image here. It has the model and make and I still can't find it anywhere: https://reverb.com/au/item/2134518-hudson-electronics-broadcast-original-run-with-nos-transistor

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    3. It's the gain switch I'm talking about.

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    4. Ah. I've seen heavier duty switches like that on Amazon and eBay before. Not sure on the specific brand or anything tho. Just search for heavy duty switch. You should get some options that way.

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    5. How to wire switches with more than two connections is what I'm not sure about.

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    6. Check out the General Layout Notes tab and look for the switch numbering diagram.

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    7. I bought one like in this link. The three connections are numbered. I assume I just hook them up to the corresponding links in the diagram above?

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    8. Thanks for you patience and help...and great layouts.

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  10. Link: http://www.homedepot.com/p/Gardner-Bender-20-Amp-Single-Pole-Toggle-Switch-1-Pack-GSW-13/100122325

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  11. How can I wire a 3pdt switch to change between low gain and high gain, and also wire a second level pot to control the low gain level and high gain level independently?
    Like this version:
    https://andertons.scdn2.secure.raxcdn.com/2/1/images/catalog/i/xl_133893-tmpB018.jpg

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  12. The TY-141P layout is confusing me. What pin# does the black dot on top of the transformer correspond to? It can't be #1 or it would have to be put in from the other side of the board.

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    1. Hi!
      TY-141p is 1:1 signal transformer, you can solder it both ways, since his windings are identical.

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    2. Thanks for the response. Still can't get it to work but you cleared one thing up. lol

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  13. There is a mistake in gain pots. Check it.

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    1. The mistake is that the resistor 5.6k is in parallel with gain pots.

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  14. hello, I built this pedal and my gain pot is acting strangly.Do you mean to say that 5.6 k connected to 1 0n gain pot and the other lead to 1nf as well as 3 on gain pot ? (or perhaps 2) the pedal seems to be working fine other than it is quite and only works with the gain knob at counterclockwise (I tried soldering the pot the other way around and it still only works counterclockwise)

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    1. You can try to use gain pot 3. You need to place 1nf between the gain pot 1 and the gain pot 2, then resistor 5.6k and pot 3 connect together. Connect potentiometer to pots 3 and 2 (pot 1 is not used for potentiometer).

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    2. Thank you very much for your response. i am having some trouble understanding. If I took a potentiometer and soldered 1nf between lug 1 and 2 and a 5.6k from lug 3 to the board and then soldered lug 2 to the board as well, would this be accurate? Part of your advice that confused me is you say to connect the potentiometer to lugs 2 and 3 of the potentiometer. If you mean to say connect lugs 2 and 3 to the board, where it says gain 2 and gain 3 on the board, this also confuses me. In that case lug 3 would be connected to nothing and lug 1 would also not be connected to the board. Note that gain 3 on the board is closest to the Corner and is not connected to any trace. Your help is greatly appreciated, as I would not have been able to find the mistake on my own. Perhaps you could clarify response by using the terms lug 1, 2, 3 for the potentiometer and board gain 1, 2,3 for traces on the board.

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  15. Maybe someone can help me diagnose my problem. I switch it on and there is a volume drop (that isn't an overdrive then dude! lol). The middle switch position is the loudest though still lower than the uneffected signal. To the right, it's slightly lower and to the left, much lower still. The knobs seem to function as they should but the overall volume just isn't coming out. Any ideas?

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    1. I've had the same problem and I think I may have found the solution, though I haven't had the time to apply it. First of all, there is a mistake with the way the 5.6k and 1nf are connected to the gain pot, as per the conversation above. You can check the schematic or I can try to describe more clearly. the other thing I've just realized is that the germanium transistoris a PNP, not an NPN as I had assumed
      I can't wait to fix it as I've been troubleshooting this pedal 5ever.

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    2. I'll sure be interested to hear how it turns out for you. BTW, are you using an OC71 as suggested or did you find a suitable replacement?

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    3. its working! this is definitely a moral booster. this pedal is very loud so you'll for sure when its working. I used TI 2N1303 PNP Ge. I think any pnp germanium will work. the 1nf cap goes between gain 1 and gain 2. gain 2 on the board goes to gain 2 on the potentiometer. 5.6 k goes in series between gain 1 on the board and gain one on the pot.

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    4. I can send you a couple of the PNPs by mail if you like, just shoot me an email.

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  16. Great! Glad you got yours going. I'll try your suggestions in the next few days when I get a chance. I appreciate the offer of the PNPs. What is your email?

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  17. I did finally get mine to work and while it sounds good, it doesn't get anywhere near the gain I was expecting. The videos I've seen have it getting downright fuzzy at the upper limit of the gain pot. Mine isn't making it there. So, two steps up and one step back for me at the moment, but I'm still working on it.

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    1. I'd start by checking the voltages on the op amp and the transistor

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    2. Alsp, you could try to run it at the end of your pedal chain and increase the volume being inputted. I had mine at the beginning, but I found it worked better right before my amp

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