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Messages - flester

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106
Amplifier Discussion / Re: Heatsinks for your poweramp
« on: December 10, 2017, 05:49:31 AM »
Does an opamp  like the lm386 need a heatsink? While testing a breadboard build i pressed down on the chip and suddenly went ouch! as it had got pretty hot. (It may have been connected wrong ny the wau)t least I willl remember the name of the chip as its branded on my finger.







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107
The Newcomer's Forum / Re: Velleman Kit 4001
« on: December 02, 2017, 02:57:56 PM »
You can't reduce gain very much, I guess minimum is around 20X , because it becomes unstable.
So reduce R2/R1 ratio to about 20:1 but not less, any ectra reduction myst be input padding."Which is not all bad, you can add a passive tone conrol which will be lossy anyway.
OK here is plan B. I've been playing around with the Lm386 opamp and decided it might suit my little enclosure better than the TDA2003. I thought id use 2 of the TDA2003 modules with each one driving a 4" car  speaker in some sort of cabinet. Maybe shaped like the Roland Street Cube https://m.thomann.de/ie/roland_cube_street_bk.htm

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108
Amplifier Discussion / USB charging
« on: November 20, 2017, 07:17:14 AM »
Lots of stuff is USB chargeable these days. Is it feasible or safe to build in USB charging to a diy amp or other builds?

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109
Amplifier Discussion / Re: NO soldering wireless guitar amp project.
« on: November 16, 2017, 05:50:28 AM »
You can always insert a pot before the transmitter to wipe off some voltage.
Agree with Joe,,,,,Cool Idea :dbtu:
Yes great idea on the pot.
What I like is that I can play my electric travel guitar in anyones house, boat, car, caravan... as long as they have an FM radio. Lucky them!

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110
Amplifier Discussion / Re: NO soldering wireless guitar amp project.
« on: November 13, 2017, 02:44:23 PM »
Thanks. My first attempt at guitar amplification was trying to connect a soundhole pickup on my acoustic into the 'hifi' in my photo. Didn't really work, maybe better impedance matching would work but I was afraid of frying the hifi.

A few steps on I made a TDA2003-based amp, it's OK but clips rather harshly. Then someone gave me the headphone amp, I had the transmitter for playing MP3s in the car, one thing lead to another and this was the result. Hey, I can now play my Hofner Shorty in the car!

The amp has 'off', 'c' (clean) and 'd'  (dirty) settings. There is basically no clean sound because the amp causes the transmitter to clip even on 'c'. The 'd' just goes to cheap and nasty distortion which I kind of like. Vox make some headphone amps designed t emulate classic amps such as the AC30....

111
Amplifier Discussion / NO soldering wireless guitar amp project.
« on: November 11, 2017, 02:28:16 PM »
Probably been done before but...
Headphone amp + fm mps transmitter +  any FM Radio = wireless guitar amp

Works well with my Technics HiFi. Using a better headphone amp (eg Vox.ones) and transmitter might improve matters. Need to keep amp volume low to stop the transmitter clipping. Little chance of hurting the receiver as the FM signal is weak enough. Plus the neighbours can hear  my killer riffs if they tune in to
106.7 FM

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112
The Newcomer's Forum / Re: Velleman Kit 4001
« on: May 27, 2016, 06:09:41 AM »
Any suggestions for preamp design?

113
The Newcomer's Forum / Re: Velleman Kit 4001
« on: May 26, 2016, 06:19:59 PM »
Mackayprod, thats cool. Are you using the Velleman kit, or just the TDA2003 chip which is at the heart of it? I got kit from Maplins (the UK/Ireland equivalent of Radio Shack)

Been playing with it again and decided I like it (or am too lazy to modify). basically I play it quiet or else flat out (wakes the family if not the neighbours) and theres no in-between. One mod I heard of is to use a smaller resistor going in to the inverting input. this increases negative feedback thus reducing the gain. I based the enclosure design on the Pignose (imitation, flattery and all that) though its a bit smaller. I put a bit of effort to fit a DC input jack and also a headphone out jack, so I can always change the guts while keeping the enclosure (of which I'm quite proud). Mainly used with my homemade Lap Steel and a Hofner Shorty guitar. Actually sounds great as a Harmonica amp too.


Letting the battery run down gives more distortion anyway (sometimes in a good way...) as Brian May did with his Deacy amp. You can now buy a Deacy replica including a variable power supply to simulate a dying battery but wheres the fun in that?

114
The Newcomer's Forum / Re: Velleman Kit 4001
« on: May 25, 2016, 05:44:50 AM »
Think iIl just accept that i can have quiet and clean or loud and dirty.  For quiet and dirty i can use my overdrive pedal. Will be back for more ideas on my next build-possibly something tiny with a 2" speaker just for fun.

115
The Newcomer's Forum / Re: Velleman Kit 4001
« on: May 24, 2016, 04:31:21 AM »
Thanks for that. It can take up to 18 v so will look for a new supply ti deliver that. Or 12 AA batteries. Would a 4 ohm speaker help?

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