Building drum machine modules - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th June 2013, 04:08 AM   #1
diyAudio Member
 
Join Date: Mar 2013
Default Building drum machine modules

Hi --

I am working on building some of the Thomas Henry drum machine modules. I have some simple questions:

1) A drum pad controller sends a +5V positive square wave out through "a jack." Should the jack be a 1/4" input? Or what about other types of connectors, like banana plugs/jacks? What is the difference between a banana jack and a 1/4" jack?

2) I am having trouble with some 741 ICs not functioning properly. They are new ICs and should be functioning properly. They are being used in the circuit as comparators. Does each 741 need a + and - power source? It looks from the schematics that some only have + or -. Maybe the problem with one of the 741s is that it is not receiving voltage in its V+ or V-?

I know this is hard to explain without the schematics. But any constructive feedback would be appreciated. Thanks!
  Reply With Quote
Old 8th June 2013, 05:29 AM   #2
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
A jack is a jack. In the USA that means a female connector. What makes it an input or output is its use. A 1/4" jack can be either. SO you might not want to refer to a "1/4" input" if you are referring to the OUTPUT of the drum trigger.

The connector you chose is up to you. It is there so you can disconnect one part from another instead of permanently wiring them together. 1/4" connectors are common in the music industry. They are also called phone connectors. (NOT phono connectors. Phono connectors is another name for RCA connectors) If you intend this to work with other commercial gear, you would want to use the same connectors as the rest of the industry. But if you are making this for yourself and it is complete without other gear, then use whatever connectors you have.

For a 5v pulse, I don't see how the type of connector matters a lot. I wouldn't use bananas myself though. If you mean what is the physical difference between the types, look them up in a catalog, that will be better than any description I could make.


Yes every op amp needs power supplies connected to it. If the IC is a single op amp, then it will need supplies. SOme ICs are dual or quad op amps, meaning ther are two or four op amp circuits in one IC. Those ICs have one common set of power pins, and all the op amps inside share it. On schematics, they often draw the power pins on one of the internal sections, so the remaining section will appear not to have power connections, but they are understood to be there from the other side.
  Reply With Quote
Old 10th June 2013, 04:04 AM   #3
diyAudio Member
 
Join Date: Mar 2013
Thanks so much for this informative answer.

1) One circuit module accepts an "input" jack and the circuit's job is to create a stable +12V pulse to send to other module units. This circuit uses a 741 op amp (I don't have the schematic in front of me), but it doesn't have the power pins on the schematic marked as hooked up. There is a chain of voltage that goes to the inverted and noninverted inputs on the opamp, but I guess what you're saying is that it should be "understood" that I hook the +V and -V to the respective voltages.

2) The second module I'm working with also has a 741, and again there are connections in the schematic to its +V or -V. This module is for a transducer drum pad that takes a transduced signal, sends it to the 741, and then sends a +5 V square wave pulse to circuit #1 above. This circuit is able to light an LED saying that it receives the hit from the drum pad, but I've tested pin #6 (the output) and there should be current coming out of it, but there is not. Maybe this is because the V+ and V- to the IC are not connected.

I'm going to keep working on this. Thank you.
  Reply With Quote
Old 10th June 2013, 10:48 PM   #4
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
If the op amp is not powered, it has nothing to output current with. All op amps must have power supply connected.
  Reply With Quote
Old 11th June 2013, 12:21 AM   #5
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by lost decade View Post
Hi --
2) I am having trouble with some 741 ICs not functioning properly. They are new ICs and should be functioning properly. They are being used in the circuit as comparators. Does each 741 need a + and - power source? It looks from the schematics that some only have + or -. Maybe the problem with one of the 741s is that it is not receiving voltage in its V+ or V-?

I know this is hard to explain without the schematics. But any constructive feedback would be appreciated. Thanks!
A 741 wont function very well as a comparator because its not a comparator and has limitations about the levels into the + and - inputs.
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 15th June 2013, 02:01 AM   #6
diyAudio Member
 
Join Date: Mar 2013
Thank you Enzo for your help. Yes, as soon as I connected the V+ and V- to the 741 the circuits worked as they were supposed to.

Nigel -- not sure about the comparator comment. The schematic says it is to function as a comparator.
  Reply With Quote
Old 15th June 2013, 03:45 AM   #7
benb is offline benb  United States
diyAudio Member
 
Join Date: Apr 2010
The 741 isn't a "great" comparator, but it probably works well enough for the circuit described.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sound Master Stix 305 drum machine valvusmusicus Parts 1 7th March 2012 03:34 AM
UcD modules - can the modules work without the input op-amp? beppe61 Class D 8 11th October 2006 07:35 AM
Analogue drum machine AMPWORSHIP Analogue Source 2 10th September 2006 02:16 PM
building the 'sample' part of an electronic drum brain beatpantz Instruments and Amps 5 16th January 2006 12:50 AM
Interested in building amps with Icepower modules mattjk Chip Amps 2 12th August 2004 09:47 PM


New To Site? Need Help?

All times are GMT. The time now is 11:46 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2