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NeuroLog System
Digitimer
Appli
cati
on N
ote
21
Using the NL405 Delay/Width Module & NL501
Logic Gate to produce pairs of pulses with interval
control from a single trigger input, such as the NL301
Pulse Generator
Here, the Neurolog System is being used to produce a repetitive single trigger pulse and convert it into a pair
of pulses with a user controllable delay between them. This pair of pulses can then be passed through an
"OR" Logic Gate (within the NL501) so that they can both be applied to one of our stimulus isolators. In this
way, a pair of stimulation pulses can be given to a preparation to study phenomena such as paired pulse
facilitation. Although the illustration shows an NL301 Pulse Generator initiating the stimuli at a certain
frequency, the initiation pulse can come from any external device capable of producing a TTL compatible logic
pulse. It is also possible to replace the NL301 with the NL304 Period Generator if slower frequencies are
required, however, because the NL304 only produces a 0.5µs output pulse, it would be necessary to employ
an extra NL405 after the NL501 Logic Gate in order to "widen" the output pulse so that it could effectively
trigger the DS2A or DS3 stimulator.
WIDTH/DELAYNL405
IN
1µs
10µs
100µs 1ms10ms
100ms
1s
0 1 0
START
fixed
retrig
+ve edge
-ve edge
DELAYED
OUT
OUT
reset
X
LOGIC GATESNL501
IN
B/1
GATE 1
2
OUT
OUT
IN
1
GATE 2
2
OUT
OUT
PULSE GEN.
NL301
50 150
500 µs
GATE
X100
X10
X1
Hz
OUT
1
3
5 7
10
12
CONTINUOUS
SINGLE
OFF
DS2A or DS3 Stimulus Isolator
(Triggered by +ve edge)
A
B
C
A
BC
Frequency set to 1Hz by NL301
(with internal jumper set for 0.05-120Hz range).
User controlled delayed pulse from NL405
set to 10 x 10ms.
1s
100ms100ms
Non-delayed and delayed pulses combined at
the NL501 Logic Gate (internally set to "OR").
Digitimer Ltd - 37 Hydeway, Welwyn Garden City, Hertfordshire, AL7 3BE Manufacturer of Clinical & Biomedical Research Instrumentation
Web: www.digitimer.com Email: [email protected] Tel: 01707 328347
