Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Effects => Topic started by: uki on October 25, 2016, 08:00:30 am

Title: EH LPB
Post by: uki on October 25, 2016, 08:00:30 am: Hey guys !

I'm working on this small boost but no go... :dontknow:

Is this schematic good working ? Also I don't have the 2n5088 , using c945 atm can this be the problem ? :help:

Thanks
Title: Re: EH LPB good schematic ?
Post by: sluckey on October 25, 2016, 08:20:03 am: Schematic looks OK. That C945 should work if you connect it correctly. Be careful. It has a different pin arrangement from the 2N5088.
Title: Re: EH LPB good schematic ?
Post by: uki on October 25, 2016, 08:34:16 am: Quote from: sluckey on October 25, 2016, 08:20:03 am
Schematic looks OK. That C945 should work if you connect it correctly. Be careful. It has a different pin arrangement from the 2N5088.

Thanks sluckey , I did check the pins , I got some others here gonna try different ones too.

Here is a simpler schematic to compare: http://fuzzcentral.ssguitar.com/schematics/lpbschem.gif (http://fuzzcentral.ssguitar.com/schematics/lpbschem.gif)
Title: Re: EH LPB good schematic ?
Post by: uki on October 25, 2016, 10:01:46 am: I've tried so far C945, BC548, BC549, 2N2222, BCY59 ... but so far all I get is radio.
What is wrong ?! :dontknow: :w2:

Hey I got it, some ground was disconnected !!
Title: Re: EH LPB good schematic ?
Post by: Ritchie200 on November 01, 2016, 08:31:40 am: Uki, you may want to check out the Linear Pro Boost+ thread a ways down in this section. Jojo could help you out on this as he has spent HOURS on this design.

Jim
Title: Re: EH LPB good schematic ?
Post by: uki on November 09, 2016, 05:59:32 pm: Oh hey Ritchie !

Thanks for the hint, I got the pedal almost done, the footswitch just arrived today, and now i can complete it !!
Also I've found a small box laying around for housing!

The 2 transistors(the ones I have) that work the best is BC945 and BCY59 this one is strong does some distortion at high level almost like a fuzz.

I got few more pics!!
Title: Re: EH LPB good schematic ?
Post by: uki on November 13, 2016, 09:20:53 am: Now that it is finished it isn't working...
Already have tried several things,checked all connections, wires, I've checked the circuit itself several times, replaced the electrolytic cap, replaced the transistor, checked for shorts, nothing... the signal dies when the switch is pressed it only work in bypass mode.
Title: Re: EH LPB good schematic ?
Post by: jojokeo on November 13, 2016, 10:44:28 am: Transistor is in backwards as Sluckey mentioned to check earlier. The original transistor used one of two tranny's with the 2n5088 being one of them. This circuit is highly dependent on the tranny used and the hFE of it. See data sheet below:
Title: Re: EH LPB good schematic ?
Post by: uki on November 13, 2016, 11:01:01 am: Yay got it , it is working !!! Thanks man !!! I was miss reading the datasheet picture, the pic shows the transistor from the botton I was reading it like it was the top... :BangHead: confusing transistor..

:happy1:

It sounds good !!

Many thanks !!
Title: Re: EH LPB
Post by: alerich on November 15, 2016, 10:01:02 pm: Good job. Glad you got it working. This is my old EH LPB-1 with the plug in 1/4" connector form the late 1970's.
Title: Re: EH LPB
Post by: uki on November 16, 2016, 12:55:25 am: Quote from: alerich on November 15, 2016, 10:01:02 pm
Good job. Glad you got it working. This is my old EH LPB-1 with the plug in 1/4" connector form the late 1970's.

Wow nice !! The original one, it is a nice pedal to overdrive the amp !!
Title: Re: EH LPB
Post by: Ed_Chambley on November 16, 2016, 09:19:15 am: Quote from: alerich on November 15, 2016, 10:01:02 pm
Good job. Glad you got it working. This is my old EH LPB-1 with the plug in 1/4" connector form the late 1970's.
Very cool you still have it.
Title: Re: EH LPB
Post by: jojokeo on January 10, 2017, 01:32:22 pm: I have that exact LPB-1 also from the 70's and used it as the basis for my Pro Boost design: It continues to sound amazing and complements everything that goes into it...http://el34world.com/Forum/index.php?topic=19969.msg216249#msg216249 (http://el34world.com/Forum/index.php?topic=19969.msg216249#msg216249)

I have a hard time letting cool old stuff go. I still have my original Maestro Fuzz Tone too.
Title: Re: EH LPB
Post by: smackoj on January 25, 2017, 07:26:54 pm: Here are a couple of the designs I have tried and they all work great. I am a big fan of using Jfets for booster pedals. They have a ton of "quiet" gain in a very small package. I keep J201 and MPF102 around my shop because they are so consistent and powerful.