Frozenstreaks
New Member
Hi everyone. This is my first post and I kinda feel bad joining this site just to get some help, but I need some help from you more experienced people. I have been in electronics for 2 years and I'm kinda stumped on this.
Here's a diagram featured at electronicsforyou.com and it's in PDF
https://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/efylinux/circuit/feb2003/aug99_IRcordless.pdf&title=Infrared%20Cordless%20Headphone]Diagram
I've been trying to build this circuit for awhile now, and it still won't work right. Here are the details if you wish to look over it. Here's a list of the parts I am using, I got the audio output transformer from radio shack. Here's a list of transistor replacements:
T1 : BC547 changed to NTE123AP
T2 : NTE374 changed to NTE374.
I'm only in need of help right now with the Transmitter part of the diagram.
The problem i have right now is at the base of T1. The signal gets clipped on the negative side and is being amplified at T1. The problem is that when i put a sine wave on it for testing (@ 700mvp-pk or @ 1vp-pk) once the sine wave gets below .7v the transistor cuts off and when it cuts off it amplifies the signal at the collector. So at the collector I have a clipped positive portion and can only adjust the negative portion of the wave with VR1. Does anyone have an idea how I can fix this? I somehow need to keep the sign wave high enough in reference to ground to keep T1 from cutting off. Thanks in advance. Any ideas welcome. I've never seen a schematic where the base divider wasn't hooked to the collector somehow.
Here's a diagram featured at electronicsforyou.com and it's in PDF
https://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/efylinux/circuit/feb2003/aug99_IRcordless.pdf&title=Infrared%20Cordless%20Headphone]Diagram
I've been trying to build this circuit for awhile now, and it still won't work right. Here are the details if you wish to look over it. Here's a list of the parts I am using, I got the audio output transformer from radio shack. Here's a list of transistor replacements:
T1 : BC547 changed to NTE123AP
T2 : NTE374 changed to NTE374.
I'm only in need of help right now with the Transmitter part of the diagram.
The problem i have right now is at the base of T1. The signal gets clipped on the negative side and is being amplified at T1. The problem is that when i put a sine wave on it for testing (@ 700mvp-pk or @ 1vp-pk) once the sine wave gets below .7v the transistor cuts off and when it cuts off it amplifies the signal at the collector. So at the collector I have a clipped positive portion and can only adjust the negative portion of the wave with VR1. Does anyone have an idea how I can fix this? I somehow need to keep the sign wave high enough in reference to ground to keep T1 from cutting off. Thanks in advance. Any ideas welcome. I've never seen a schematic where the base divider wasn't hooked to the collector somehow.
